Psychological Reports, 1975, 37, 1067-1073. @ Psychological Reports 1975
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
R. T. OSBORNE Univerrity of Georgia Summary.-All Georgia children in Grades 4, 8, and 12 (250,000) were given mental ability and reading and arithmetic achievement tests in the Fall of 1971. Four demographic variables from the 1970 census, the educational expendimre per child, average daily attendance, and 12 test variables were intercorrelated. All correlations between mental ability and fertility ratios are negative. All are significant. Also, all correlations between fertility ratios and measures of school achievement are negative and significant. Per capita expenditure does not have a significant effect on school achievement at any grade level.
Recently in separate papers Waller ( 17 ) reported positive relationships between fertility and education, occuparion, and IQ; Vandenberg ( 16) reported at the Ninth International Congress of Anthropological and Ethnological Sciences, "All measurable evidence to date showed no decline [in IQ]. . . . Intelligence is presumably controlled by so many genes that the average and below-average person will carry a number of genes for high ability which he will at times transmit to his offspring." These reassuring and optimistic studies not only discount the earlier investigations of Burt ( 1 ) and Cattell ( I ) , but they are also discordant with the contemporary works of Campbell and Kiser ( 2 ) and Frederick Osborn (10). Waller attributed the important difference between his findings and the earlier studies to prior faulty methodology. He calculated the intrinsic rate of natural increase and generation length for IQ test score and educational attainment groups and concluded that "natural selection is favoring an increase in mean IQ score in the sample of the present study, or at least there is no evidence for decrease." Vandenberg ( 1 6 ) claims all measurable evidence to date shows no decline in intelligence. His conclusions are based on a comparison of 11-yr.-old children in Scotland in 1932 and in 1947 and the results of a Belgian study comparing children of five socioeconomic groups. Discrepancies between the faintly eugenic reports of Vandenberg and Waller and the dysgenic findings of Burt and Cactell are not related to faulty methodology but rather to misinterpretations of the Vandenberg and Waller manuscripts in generalizing to the United States as a whole from restricted samples which "exclude nonwhite persons." In a review of Waller's 1970 paper and the well-known Minnesota studies, Cattell (personal communication, 1972) notes that "by any proper conception of our national life and its trends, one must include the Negro population which these studies have excluded." In 1971, Campbell and Kiser ( 2 ) reported the birthrate of the nonwhite population of the United States to be higher than that of the white population
1068
R. T. OSBORNE
at all socioeconomic levels except the highest, where it dropped below the white. Fertility ratios are tied to age at marriage, housing, and education, i.e., the lower the level of any of these three, the higher the birthrate. Frederik Osborn ( 1 0 ) sees as dangerous, if continued for long, the trend for blacks with a better education to have families smaller than corresponding whites, while low socioeconomic group blacks have more children than correspond;ng whites. In the present study, U.S. Census demographic variables, educational cost per child, average daily attendance, and school achievement and IQ data were collated and analyzed to determine for the state of Georgia the relationship between IQ of public school children and the birthrate (fertility ratio) of their county of residence; that is, with respect to IQ and school achievement, is the trend in Georgia dysgenic or eugenic? In addition to the fertility ratio, three other census variables-population, percent change in population since 1960, and percent nonwhite population-were examined in terms of their relationship to basic educational parameters, IQ, and reading and arithmetic achievement. Furthermore, the relationships between educational cost per child and the scholastic variables were considered.
METHOD The population of Georgia in 1970 was 4% million made up of 73.9% white, 25.9% black, and .2% other races. From the 1970 Census of Population ( 1 5 ) the following information for the 159 Georgia counties was obtained: ( a ) population-the range was from that of a small rural county, less than 2,000, to that of a large metropolitan county, over 600,000, ( b ) percent increase since 1960 census-the range of change was from -28% to 11196, range of nonwhite population was from 0 % In (c) percent nonwhite population-the one Georgia county to 74% in another; ( d ) fertility rati-the range of the fertility ratio by county was from 267 to 520. Census figures are simple numbers or percents, except the fertility ratio which is a straightforward definition of fertility that, in one index number, accounts for nonreproducing adults, marital status of parents, etc. The U.S. Census of Population defines fertility as the number of children under five per 1,000 women 15 to 4 9 yr. of age. All Georgia children in Grades 4, 8, and 12 (250,000) were given mental ability and reading and arithmetic achievement tests in the Fall of 1971 The Cognitive Abilities Test ( 1 4 ) and the Iowa Tests of Basic Skills ( 9 ) were administered to srud-nts in Grades 4 and 8 and the Cognitive Abilities Test and Tests of Academic Progress ( 1 1 ) were administered to students in Grade 12. The results of the testing program, the average daily attendance, and records of educational expense per child for each Georgia counry were obtained from the published reports of the State Department of Education (12, 1 3 ) . Four demographic variables from the 1970 census, the educational expenditure per child, average daily attendance, and 1 2 school variables (four for each of three grades) were intercorrelated by the product-moment method. In order to determine the unique contribution of birthrate to intelligence and school achievement, 48 separate regression analyses were computed with the criterion for each being one of the school variables: verbal IQ, nonverbal IQ, reading achievement, or arithmetic achievement for Grades 4, 8, and 12. The R2s were found for four models:
+
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
1069
( a ) the regression of county population, percent population change since 1960. percent nonwhite population, and fertility ratio on each of the 12 criteria; ( b ) the regression of the first three census variables on the criteria; (c) the regression of percent nonwhite population and fertility ratio on the independent variables; ( d ) the regression of only nonwhite population on the crireria. Consequently, ic was possible to have two testiogs of the null hypothesis to determine the unique contribution of fertility ratio to each criterion by comparing the coefficients of determination for the four-predictor model with the three-predictor model and also the two-predictor and one-predictor models. For example, the difference in R's of the full, four-predictor model and the restricted, three-predictor model is a measure of the predictive value of the variable deleted from the full model ( 7 ) . In order to determine the unique contribution of educational expenditure per child to intelligence and school achievement, the regression analysis described above was repeated except educational expenditure and average daily attendance were added as predictors. That is, the full model contained population, population change, percent nonwhite, fertiliry ratio, expendimre per child, and average daily attendance. In the restricted model, expenditure per child was dropped out to enable comparison between the two models.
RESULTS
During the 1960-70 decade, Georgia counties of larger populations grew at a faster rate than did the smaller counties. The increase, however, was due to inmigration, since the fertility ratios (birthrates) of the more populous counties were lower than those for smaller counties. For example, the fertility index of the largest county in Georgia was 325, while percent increase since 1960 was 9.2. For a county near the state population median the fertility ratio was 408; the percent population increase since 1960 was 5.9. For Georgia's smallest county, the fertility ratio was 393, but the 10-yr. increase was only 2.6%. This trend for larger counties to increase in population at a faster rate than smaller counties, in spite of a lower fertility ratio, is evident throughout Georgia. The correlation between percentage gain during the decade and population is .27 (see Table 1 ) . Since the percentage gain in population is negatively related to minority population ( 7 = -.49), those counties with relatively smzll black populations are growing at a faster rate than those with large nonwhite populations. The one county which more than doubled in population berween 1960 and 1970 had only 5% black population. Four of Georgia's 159 counties showed a net loss of 20% or more population for the decade. The birthrate (fertility ratio) for those counties was above the state average, but the percent black population was above 55% in all four counties. The correlation berween fertility ratio and mean IQ is negative for both verbal and nonverbal IQ, i.e., the greater the number of children under five yr. per 1,000 women from 15 to 49 yr., the lower the mean IQ for the county (Table 1 ) . These correlzltions are consistent for all three grades and range The rs are significant and are greater than the -.26 from -.43 to -.54.
TABLE 1 C~RRELATION hfATRM FOR GEORGIASCHOOLCHILDRENIN GRADES4, 8, AND 12 FOR IQ, ACHIEVEMENT,CENSUS VARIABLES, EDUCATIONALCOST PER CHILD AND AVERAGEDAILYATTENDANCE
2 1970 U.S. Census Variables 1. Population 2. Percent Increase in Population 3. Percent Non-white 4. Fertility Ratio Georgia State Dept of Education Records 5. Average Daily Attendance 6. Cost of Education per Child Test Results 7. Grade 4 Reading 8. Grade 4 Mathematics 9. Grade 4 Verbal IQ 10. Grade 4 Non-verbal IQ 11. Grade 8 Reading 12. Grade 8 Mathematics 13. Grade 8 Verbal IQ 14. Grade 8 Non-verbal 1Q 15. Grade 12 Reading 16. Grade 12 Mathematics 17. Grade 12 Verbal Aptitude 18. Grade 12 Non-verbal Aptitude Note.--r = .16, at p = .05; r = .21, at p
3
4
5
6
7
8
9
10
11
.27 -.I1 -.30 .99 .20 -.49 -.12 .30 -.31 .47 -.I2 .47 -.29 .14
.23 .44 -.73 -.52
.22 .41 -.69 -.49
.25 .40 -.67 -.52
.27 .50 -.66 -.46
.26 .54 -.82 -.54
.17
12
13
14
15
16
17
18
.24 .31 .34 .29 .33 .47 .52 .53 .50 .46 - 3 0 -31 -30 -.80 -.70 -.52 -.54 -.51 -.46 -.47
.34 .50 -.80 -.51
.36 .53 -.79 -.43
.26 .24 .27 .30 .29 .26 .34 .36 .31 .35 .36 .38 -.29 -.I7 -.24 -31 -.37 -.31 -.33 -31 -.39 -.33 -.40 -.37
?' 9 0
V,
.91 .92 .87 .84 .88 .82 .77 .87 .78 .82
= .01.
.82 .77 .78 .76 .93
.84 .77 .80 .82 .97 .93
.82 .75 .77 .80 .92 .90 .95
.75 .68 .68 .72 .86 .83 .85 .83
.71 .67 .66 .71 .82 .79 .80 .79 .89
.75 .69 .68 .73 .86 .83 .85 .85 .97 .90
.74 .69 .66 .71 .83 .80 .83 .83 .92 .89 .95
$2
5
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
1071
reported in a recent study by Cattell who used children per family as an index of fertility instead of the census defined fertility ratio ( 4 ) . This dysgenic trend is also seen in the rs between fertility and reading and arithmetic achievement, i.e., the higher the county birthrate, the lower the reading and the arithmetic achievement scores of the children of the county. Again, findings are consistent for both reading and arithmetic achievemenc for all three grades. It will come as a surprise to some educational reformers, but not to Coleman ( 5 ) , that educational expenditure does not have a notable, positive effect on school achievement. In Georgia, correlations are significantly negative between educational cost per child and reading and arithmetic achievemenc and IQ for all three grades (Table 1 ) . In Table 2, R2s for the four-predictor model and the restricted, threepredictor model are shown along with the F statistics for determining the significance of the unique contribution of fertility ratio to school achievement and test intelligence for the three grades studied. The differences becween the coefficients of determination for the two models are significant at the ,001 level for all criteria for Grades 4 and 8. The evidence is not as convincing for Grade 12 but, still, two of the four comparisons made for this grade are significant at the .05 level or beyond. At Grade 12, reading achievement and nonverbal I Q predictions are not enhanced significantly by the addition of the fertility racio to the regression analysis. In the second analysis (Table 3 ) , in the full model, percent nonwhite and fertility ratio are the predictors. In the restricted model, fertility racio is dropped out leaving only percent nonwhite as a predictor. From Table 3 it is seen that the birthrate of a county is a significant predictor of school achievement and IQ at the fourth and eighth grade levels. Again, confidence levels are attenuated at the 12th grade, but three of the four comparisons are significant at the .05 level or beyond. From the present data there is no way to account for the attenuated R 3 at the 12th grade. However, in Georgia school ,
TABLE 2 UNIQUE CONTRIBUT~ON OF FERTILITY RAT10 TO SCHOOL ACHIEVEMENT A N D IQ FOR 159 GEORGIA COUNTIES: COMPARISONOF FULL (POPULATION, POPULATION CHANGE,PERCENT NON-WHITE, AND FERTILITYRATIO) AND RESTRIC~ED (POPULATION, POPULATION CHANGE, AND PERCENTNON-WHITE) REGRESSIONMODELS Criterion Reading Mathematics Verbal IQ Quantitative IQ *dfs of 1 and 154.
Grade 4
R I R,= ~ .GO .52 .53 .53
F*
R,",=
.57 12.59 .001 .50 8.85 .005 .49 13.24 ,001 .50 8.58 .005
.74 .69 .74 .72
Grade 8 F*
-
p
.71 15.59 ,001 .67 9.42 ,005 .72 11.60 .001 .71 6.46 ,025
~ r a d e12R,' Rr3 P'' 0 .69 .57 .72 .71
68 1.67 .ZOO 5 5 5.22 ,025 .71 5.35 ,025 .71 0.05
1072
R. T. OSBORNE
TABLE 3 UNIQUECONTRIBUTION OF F E R T l L l n RATIOTO SCHOOL ACHIEVEMENT AND 1Q FOR 159 GEORGIA COUNTIES:COMPARISON OF FULL (PERCENTNON-WHITEAND F E R T ~ L ~RATIO) ~Y AND RESTRICTED(PERCENTNON-WHITE) REGRESSION MODELS Criterion Reading Mathematics Verbal IQ Quantitative IQ *dfs of 1 and 156.
Grade 4 Rr2 R,' F* fl
R,",'
.58 .51 .51 .47
.70 .67 .69 .66
.54 14.88 .47 10.84 .46 16.91 $44 8.85
,001 .005 .001 ,005
Grade 8 F* P .66 .64 .G6 .64
15.84 12.22 16.10 10.60
,001 ,001 ,001 .005
Grade 12 R,' Rr2 F* .65 .51 .67 .63
P
.64 4.13 ,050 .49 8.94 ,005 .64 10.61 .005 .63 1.56
dropout rate is accelerated after age 16. In the Fall of 1971, there were 83,000 children in the eighth grade and only 53,000 in the 12th grade. From Table 4, it is evident thac expenditure per child is not a significant predictor of IQ, reading, or arithmetic achievement when knowledge of the other predictors is known. Of the 12 criteria, only the analysis of the fourth grade arithmetic was significantly influenced by the unique contribution of expenditure per child. TABLE 4 UNIQUECONTRIBUTION OF EXPENDITURE PER CHILDTO SCHOOLACH~EVEMENT AND IQ FOR 159 GEORGIA COUNTIES:COMPARISON OF FULL (POPULATION, POPULATION CHANGE, PERCENTNON-WHITE,FERTILITY RATIO,EXPENDITURE PER CHILD,AND AVERAGEDAILYATTENDANCE) AND RESTRICTED (POPULATION, POPULATION CHANGE,PERCENTNON-WHITE,FERTILI~RATIO, AND AVERAGE DAILYA ~ N D A N C E )REGRESSION MODELS Criterion
Grade 4 ~
Reading Mathematics Verbal IQ Quantitative IQ 4:dfs of 1 and 152.
,
.62 .58 .57 .55
R,'
1
F*
g
.62 1.66 .55 11.61 .01 .57 2.27 .55 0.00
R,Qr2 .76 .71 .76 .75
Grade 8 F*
.76 .70 .76 .75
0.06 2.35 1.07 1.08
Grade 12 D
R,' R",* .69 .59 .74 .73
.69 .59 .73 .72
D 1.49 0.70 3.38 0.89
It should be noted, in conclusion, thac in contrast with the findings in Minnesota, our results show a dysgenic trend. All correlations between mental ability and fertility ratios are negative. All are significant. T h e independent contribution of fertiliry ratio to school achievement and IQ is confirmed by significant increases in the coefficients of determination when fertility ratio is added to the regression analyses. Per capita expenditure does not have a notable positive, effect o n school achievement a t any grade level. O n the contrary, in Georgia the relationship between educational cost per child and reading and arithmetic achievement is negative. In fact, the unique predictive contribution
FERTILITY, 1Q A N D SCHOOL ACHIEVEMENT
1073
of expenditure per child was generally nonsignificant when knowledge of relevant census data and average daily atcendance is known. Discordance in the findings between Waller (17) and Higgins, et al. (8) and those of Burt ( I ) , Cattell ( 3 ) , and Conrad and Jones (6) is independent of methodology but is related to the populations sampled. Waller (17) points out in the summary of his paper that conclusions should be limited to the all white population of Minnesota. The present study is based on the 1970 population census for Georgia. Twenty-six percent of the population of Georgia is nonwhite. The discrepancies between the findings of the Georgia and Minnesota studies point up the urgent need for expert and intensive investigations of the fertility-IQ controversy as related to national programs of education, welfare, and family planning. REFERENCES 1. BURT, C. Occasional Paperr on Eugenics, N o . 2. London, Eng.: Hamilton, 1946. 2. CAMPBELL, A. A,, & K I S ~ R ,C. V. Nonwhite fertility and family planning. I n R . H. Osborne ( E d . ) , B~ologrcaland social meaning o f race. San Francisco: Freeman, 1971. Pp. 135-148. 3. CATTELL,R. B. T h e fate of national intelligence: test of a thirteen-year prediction. Eugen. Rev., 1951, 142, 136-148. 4. CARELL, R. B. Differential fertility and natural selection in society for IQ: some required conditions in their investigation. (Personal correspondence, 1972) 5. COLEMAN,J. S. Equality o f educational opportunity. Washington, D . C . : U. S. , Gov't Print. Off.. 1966. 6. CONRAD,H. S., & H. E. A field study of the differential birth rate. I . Amer. Stat. Assn, 1932, 27, 153-159. 7. DARLINGTON,R. B. Multiple regression in psychological research and practice. Psychol. Bull., 1968, 67, 161-182. 8. HIGGINS,J. V., REED, E. W., & REED, S. C. lntelligence and family size: a paradox resolved. Eugen. Qumt., 1962, 9, 84-90. 9. LINDQUIST, E. F., & HIERONYMUS,A. N. Iozua Tests o f Basic Skillr. Boston: Houghton Mifflin, 1955-73. 10. OSBORN,F. Races and the future of man. In R. H. Osbotne (Ed.), Biological and social meaning o f .lace. San Francisco: Freeman, 1971. Pp. 149-157. 11. SCANNELL.D. P., et al. Tests o f Academic Progress. Boston: Houghton Mifflin, 1964-66. 12. STATE DEPARTMENTOF EDUCATION. Annual Report--Georgia Department of Education, 1970-71. Atlanta, Ga.: Author, 1971. 13. STATEDEPARTMENTOF EDUCATION. Statewide testing program, 1971-72. Atlanta, Ga.: Stare Dept. Educ., 1972. 14. THORNDIKE,R. L., & HAGEN,E. P. Cognitive Abilities Test, Multilevel Edition. Boston: Houghton Mifflin, 1973. 15. U. S. BUREAUO F CENSUS. Censrrs o f population: 1970. General population characteristics. Final Report P C ( 1 ) - B I Z , Georgia. Washington, D. C . : U. S. Gov'c Print. Off., 1971. S. G. LOS Angeles Times, Sept. 9, 1973. 16. VANDENBERG, 17. WALLER,J. H. Differential reproduction: its relation to I Q test score, education, and occupation. Soc. Biol., 1970, 18, 122-136.
JONES,
Accepted September 2, 1975.
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
R. T. OSBORNE Univerrity of Georgia Summary.-All Georgia children in Grades 4, 8, and 12 (250,000) were given mental ability and reading and arithmetic achievement tests in the Fall of 1971. Four demographic variables from the 1970 census, the educational expendimre per child, average daily attendance, and 12 test variables were intercorrelated. All correlations between mental ability and fertility ratios are negative. All are significant. Also, all correlations between fertility ratios and measures of school achievement are negative and significant. Per capita expenditure does not have a significant effect on school achievement at any grade level.
Recently in separate papers Waller ( 17 ) reported positive relationships between fertility and education, occuparion, and IQ; Vandenberg ( 16) reported at the Ninth International Congress of Anthropological and Ethnological Sciences, "All measurable evidence to date showed no decline [in IQ]. . . . Intelligence is presumably controlled by so many genes that the average and below-average person will carry a number of genes for high ability which he will at times transmit to his offspring." These reassuring and optimistic studies not only discount the earlier investigations of Burt ( 1 ) and Cattell ( I ) , but they are also discordant with the contemporary works of Campbell and Kiser ( 2 ) and Frederick Osborn (10). Waller attributed the important difference between his findings and the earlier studies to prior faulty methodology. He calculated the intrinsic rate of natural increase and generation length for IQ test score and educational attainment groups and concluded that "natural selection is favoring an increase in mean IQ score in the sample of the present study, or at least there is no evidence for decrease." Vandenberg ( 1 6 ) claims all measurable evidence to date shows no decline in intelligence. His conclusions are based on a comparison of 11-yr.-old children in Scotland in 1932 and in 1947 and the results of a Belgian study comparing children of five socioeconomic groups. Discrepancies between the faintly eugenic reports of Vandenberg and Waller and the dysgenic findings of Burt and Cactell are not related to faulty methodology but rather to misinterpretations of the Vandenberg and Waller manuscripts in generalizing to the United States as a whole from restricted samples which "exclude nonwhite persons." In a review of Waller's 1970 paper and the well-known Minnesota studies, Cattell (personal communication, 1972) notes that "by any proper conception of our national life and its trends, one must include the Negro population which these studies have excluded." In 1971, Campbell and Kiser ( 2 ) reported the birthrate of the nonwhite population of the United States to be higher than that of the white population
1068
R. T. OSBORNE
at all socioeconomic levels except the highest, where it dropped below the white. Fertility ratios are tied to age at marriage, housing, and education, i.e., the lower the level of any of these three, the higher the birthrate. Frederik Osborn ( 1 0 ) sees as dangerous, if continued for long, the trend for blacks with a better education to have families smaller than corresponding whites, while low socioeconomic group blacks have more children than correspond;ng whites. In the present study, U.S. Census demographic variables, educational cost per child, average daily attendance, and school achievement and IQ data were collated and analyzed to determine for the state of Georgia the relationship between IQ of public school children and the birthrate (fertility ratio) of their county of residence; that is, with respect to IQ and school achievement, is the trend in Georgia dysgenic or eugenic? In addition to the fertility ratio, three other census variables-population, percent change in population since 1960, and percent nonwhite population-were examined in terms of their relationship to basic educational parameters, IQ, and reading and arithmetic achievement. Furthermore, the relationships between educational cost per child and the scholastic variables were considered.
METHOD The population of Georgia in 1970 was 4% million made up of 73.9% white, 25.9% black, and .2% other races. From the 1970 Census of Population ( 1 5 ) the following information for the 159 Georgia counties was obtained: ( a ) population-the range was from that of a small rural county, less than 2,000, to that of a large metropolitan county, over 600,000, ( b ) percent increase since 1960 census-the range of change was from -28% to 11196, range of nonwhite population was from 0 % In (c) percent nonwhite population-the one Georgia county to 74% in another; ( d ) fertility rati-the range of the fertility ratio by county was from 267 to 520. Census figures are simple numbers or percents, except the fertility ratio which is a straightforward definition of fertility that, in one index number, accounts for nonreproducing adults, marital status of parents, etc. The U.S. Census of Population defines fertility as the number of children under five per 1,000 women 15 to 4 9 yr. of age. All Georgia children in Grades 4, 8, and 12 (250,000) were given mental ability and reading and arithmetic achievement tests in the Fall of 1971 The Cognitive Abilities Test ( 1 4 ) and the Iowa Tests of Basic Skills ( 9 ) were administered to srud-nts in Grades 4 and 8 and the Cognitive Abilities Test and Tests of Academic Progress ( 1 1 ) were administered to students in Grade 12. The results of the testing program, the average daily attendance, and records of educational expense per child for each Georgia counry were obtained from the published reports of the State Department of Education (12, 1 3 ) . Four demographic variables from the 1970 census, the educational expenditure per child, average daily attendance, and 1 2 school variables (four for each of three grades) were intercorrelated by the product-moment method. In order to determine the unique contribution of birthrate to intelligence and school achievement, 48 separate regression analyses were computed with the criterion for each being one of the school variables: verbal IQ, nonverbal IQ, reading achievement, or arithmetic achievement for Grades 4, 8, and 12. The R2s were found for four models:
+
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
1069
( a ) the regression of county population, percent population change since 1960. percent nonwhite population, and fertility ratio on each of the 12 criteria; ( b ) the regression of the first three census variables on the criteria; (c) the regression of percent nonwhite population and fertility ratio on the independent variables; ( d ) the regression of only nonwhite population on the crireria. Consequently, ic was possible to have two testiogs of the null hypothesis to determine the unique contribution of fertility ratio to each criterion by comparing the coefficients of determination for the four-predictor model with the three-predictor model and also the two-predictor and one-predictor models. For example, the difference in R's of the full, four-predictor model and the restricted, three-predictor model is a measure of the predictive value of the variable deleted from the full model ( 7 ) . In order to determine the unique contribution of educational expenditure per child to intelligence and school achievement, the regression analysis described above was repeated except educational expenditure and average daily attendance were added as predictors. That is, the full model contained population, population change, percent nonwhite, fertiliry ratio, expendimre per child, and average daily attendance. In the restricted model, expenditure per child was dropped out to enable comparison between the two models.
RESULTS
During the 1960-70 decade, Georgia counties of larger populations grew at a faster rate than did the smaller counties. The increase, however, was due to inmigration, since the fertility ratios (birthrates) of the more populous counties were lower than those for smaller counties. For example, the fertility index of the largest county in Georgia was 325, while percent increase since 1960 was 9.2. For a county near the state population median the fertility ratio was 408; the percent population increase since 1960 was 5.9. For Georgia's smallest county, the fertility ratio was 393, but the 10-yr. increase was only 2.6%. This trend for larger counties to increase in population at a faster rate than smaller counties, in spite of a lower fertility ratio, is evident throughout Georgia. The correlation between percentage gain during the decade and population is .27 (see Table 1 ) . Since the percentage gain in population is negatively related to minority population ( 7 = -.49), those counties with relatively smzll black populations are growing at a faster rate than those with large nonwhite populations. The one county which more than doubled in population berween 1960 and 1970 had only 5% black population. Four of Georgia's 159 counties showed a net loss of 20% or more population for the decade. The birthrate (fertility ratio) for those counties was above the state average, but the percent black population was above 55% in all four counties. The correlation berween fertility ratio and mean IQ is negative for both verbal and nonverbal IQ, i.e., the greater the number of children under five yr. per 1,000 women from 15 to 49 yr., the lower the mean IQ for the county (Table 1 ) . These correlzltions are consistent for all three grades and range The rs are significant and are greater than the -.26 from -.43 to -.54.
TABLE 1 C~RRELATION hfATRM FOR GEORGIASCHOOLCHILDRENIN GRADES4, 8, AND 12 FOR IQ, ACHIEVEMENT,CENSUS VARIABLES, EDUCATIONALCOST PER CHILD AND AVERAGEDAILYATTENDANCE
2 1970 U.S. Census Variables 1. Population 2. Percent Increase in Population 3. Percent Non-white 4. Fertility Ratio Georgia State Dept of Education Records 5. Average Daily Attendance 6. Cost of Education per Child Test Results 7. Grade 4 Reading 8. Grade 4 Mathematics 9. Grade 4 Verbal IQ 10. Grade 4 Non-verbal IQ 11. Grade 8 Reading 12. Grade 8 Mathematics 13. Grade 8 Verbal IQ 14. Grade 8 Non-verbal 1Q 15. Grade 12 Reading 16. Grade 12 Mathematics 17. Grade 12 Verbal Aptitude 18. Grade 12 Non-verbal Aptitude Note.--r = .16, at p = .05; r = .21, at p
3
4
5
6
7
8
9
10
11
.27 -.I1 -.30 .99 .20 -.49 -.12 .30 -.31 .47 -.I2 .47 -.29 .14
.23 .44 -.73 -.52
.22 .41 -.69 -.49
.25 .40 -.67 -.52
.27 .50 -.66 -.46
.26 .54 -.82 -.54
.17
12
13
14
15
16
17
18
.24 .31 .34 .29 .33 .47 .52 .53 .50 .46 - 3 0 -31 -30 -.80 -.70 -.52 -.54 -.51 -.46 -.47
.34 .50 -.80 -.51
.36 .53 -.79 -.43
.26 .24 .27 .30 .29 .26 .34 .36 .31 .35 .36 .38 -.29 -.I7 -.24 -31 -.37 -.31 -.33 -31 -.39 -.33 -.40 -.37
?' 9 0
V,
.91 .92 .87 .84 .88 .82 .77 .87 .78 .82
= .01.
.82 .77 .78 .76 .93
.84 .77 .80 .82 .97 .93
.82 .75 .77 .80 .92 .90 .95
.75 .68 .68 .72 .86 .83 .85 .83
.71 .67 .66 .71 .82 .79 .80 .79 .89
.75 .69 .68 .73 .86 .83 .85 .85 .97 .90
.74 .69 .66 .71 .83 .80 .83 .83 .92 .89 .95
$2
5
FERTILITY, IQ AND SCHOOL ACHIEVEMENT
1071
reported in a recent study by Cattell who used children per family as an index of fertility instead of the census defined fertility ratio ( 4 ) . This dysgenic trend is also seen in the rs between fertility and reading and arithmetic achievement, i.e., the higher the county birthrate, the lower the reading and the arithmetic achievement scores of the children of the county. Again, findings are consistent for both reading and arithmetic achievemenc for all three grades. It will come as a surprise to some educational reformers, but not to Coleman ( 5 ) , that educational expenditure does not have a notable, positive effect on school achievement. In Georgia, correlations are significantly negative between educational cost per child and reading and arithmetic achievemenc and IQ for all three grades (Table 1 ) . In Table 2, R2s for the four-predictor model and the restricted, threepredictor model are shown along with the F statistics for determining the significance of the unique contribution of fertility ratio to school achievement and test intelligence for the three grades studied. The differences becween the coefficients of determination for the two models are significant at the ,001 level for all criteria for Grades 4 and 8. The evidence is not as convincing for Grade 12 but, still, two of the four comparisons made for this grade are significant at the .05 level or beyond. At Grade 12, reading achievement and nonverbal I Q predictions are not enhanced significantly by the addition of the fertility racio to the regression analysis. In the second analysis (Table 3 ) , in the full model, percent nonwhite and fertility ratio are the predictors. In the restricted model, fertility racio is dropped out leaving only percent nonwhite as a predictor. From Table 3 it is seen that the birthrate of a county is a significant predictor of school achievement and IQ at the fourth and eighth grade levels. Again, confidence levels are attenuated at the 12th grade, but three of the four comparisons are significant at the .05 level or beyond. From the present data there is no way to account for the attenuated R 3 at the 12th grade. However, in Georgia school ,
TABLE 2 UNIQUE CONTRIBUT~ON OF FERTILITY RAT10 TO SCHOOL ACHIEVEMENT A N D IQ FOR 159 GEORGIA COUNTIES: COMPARISONOF FULL (POPULATION, POPULATION CHANGE,PERCENT NON-WHITE, AND FERTILITYRATIO) AND RESTRIC~ED (POPULATION, POPULATION CHANGE, AND PERCENTNON-WHITE) REGRESSIONMODELS Criterion Reading Mathematics Verbal IQ Quantitative IQ *dfs of 1 and 154.
Grade 4
R I R,= ~ .GO .52 .53 .53
F*
R,",=
.57 12.59 .001 .50 8.85 .005 .49 13.24 ,001 .50 8.58 .005
.74 .69 .74 .72
Grade 8 F*
-
p
.71 15.59 ,001 .67 9.42 ,005 .72 11.60 .001 .71 6.46 ,025
~ r a d e12R,' Rr3 P'' 0 .69 .57 .72 .71
68 1.67 .ZOO 5 5 5.22 ,025 .71 5.35 ,025 .71 0.05
1072
R. T. OSBORNE
TABLE 3 UNIQUECONTRIBUTION OF F E R T l L l n RATIOTO SCHOOL ACHIEVEMENT AND 1Q FOR 159 GEORGIA COUNTIES:COMPARISON OF FULL (PERCENTNON-WHITEAND F E R T ~ L ~RATIO) ~Y AND RESTRICTED(PERCENTNON-WHITE) REGRESSION MODELS Criterion Reading Mathematics Verbal IQ Quantitative IQ *dfs of 1 and 156.
Grade 4 Rr2 R,' F* fl
R,",'
.58 .51 .51 .47
.70 .67 .69 .66
.54 14.88 .47 10.84 .46 16.91 $44 8.85
,001 .005 .001 ,005
Grade 8 F* P .66 .64 .G6 .64
15.84 12.22 16.10 10.60
,001 ,001 ,001 .005
Grade 12 R,' Rr2 F* .65 .51 .67 .63
P
.64 4.13 ,050 .49 8.94 ,005 .64 10.61 .005 .63 1.56
dropout rate is accelerated after age 16. In the Fall of 1971, there were 83,000 children in the eighth grade and only 53,000 in the 12th grade. From Table 4, it is evident thac expenditure per child is not a significant predictor of IQ, reading, or arithmetic achievement when knowledge of the other predictors is known. Of the 12 criteria, only the analysis of the fourth grade arithmetic was significantly influenced by the unique contribution of expenditure per child. TABLE 4 UNIQUECONTRIBUTION OF EXPENDITURE PER CHILDTO SCHOOLACH~EVEMENT AND IQ FOR 159 GEORGIA COUNTIES:COMPARISON OF FULL (POPULATION, POPULATION CHANGE, PERCENTNON-WHITE,FERTILITY RATIO,EXPENDITURE PER CHILD,AND AVERAGEDAILYATTENDANCE) AND RESTRICTED (POPULATION, POPULATION CHANGE,PERCENTNON-WHITE,FERTILI~RATIO, AND AVERAGE DAILYA ~ N D A N C E )REGRESSION MODELS Criterion
Grade 4 ~
Reading Mathematics Verbal IQ Quantitative IQ 4:dfs of 1 and 152.
,
.62 .58 .57 .55
R,'
1
F*
g
.62 1.66 .55 11.61 .01 .57 2.27 .55 0.00
R,Qr2 .76 .71 .76 .75
Grade 8 F*
.76 .70 .76 .75
0.06 2.35 1.07 1.08
Grade 12 D
R,' R",* .69 .59 .74 .73
.69 .59 .73 .72
D 1.49 0.70 3.38 0.89
It should be noted, in conclusion, thac in contrast with the findings in Minnesota, our results show a dysgenic trend. All correlations between mental ability and fertility ratios are negative. All are significant. T h e independent contribution of fertiliry ratio to school achievement and IQ is confirmed by significant increases in the coefficients of determination when fertility ratio is added to the regression analyses. Per capita expenditure does not have a notable positive, effect o n school achievement a t any grade level. O n the contrary, in Georgia the relationship between educational cost per child and reading and arithmetic achievement is negative. In fact, the unique predictive contribution
FERTILITY, 1Q A N D SCHOOL ACHIEVEMENT
1073
of expenditure per child was generally nonsignificant when knowledge of relevant census data and average daily atcendance is known. Discordance in the findings between Waller (17) and Higgins, et al. (8) and those of Burt ( I ) , Cattell ( 3 ) , and Conrad and Jones (6) is independent of methodology but is related to the populations sampled. Waller (17) points out in the summary of his paper that conclusions should be limited to the all white population of Minnesota. The present study is based on the 1970 population census for Georgia. Twenty-six percent of the population of Georgia is nonwhite. The discrepancies between the findings of the Georgia and Minnesota studies point up the urgent need for expert and intensive investigations of the fertility-IQ controversy as related to national programs of education, welfare, and family planning. REFERENCES 1. BURT, C. Occasional Paperr on Eugenics, N o . 2. London, Eng.: Hamilton, 1946. 2. CAMPBELL, A. A,, & K I S ~ R ,C. V. Nonwhite fertility and family planning. I n R . H. Osborne ( E d . ) , B~ologrcaland social meaning o f race. San Francisco: Freeman, 1971. Pp. 135-148. 3. CATTELL,R. B. T h e fate of national intelligence: test of a thirteen-year prediction. Eugen. Rev., 1951, 142, 136-148. 4. CARELL, R. B. Differential fertility and natural selection in society for IQ: some required conditions in their investigation. (Personal correspondence, 1972) 5. COLEMAN,J. S. Equality o f educational opportunity. Washington, D . C . : U. S. , Gov't Print. Off.. 1966. 6. CONRAD,H. S., & H. E. A field study of the differential birth rate. I . Amer. Stat. Assn, 1932, 27, 153-159. 7. DARLINGTON,R. B. Multiple regression in psychological research and practice. Psychol. Bull., 1968, 67, 161-182. 8. HIGGINS,J. V., REED, E. W., & REED, S. C. lntelligence and family size: a paradox resolved. Eugen. Qumt., 1962, 9, 84-90. 9. LINDQUIST, E. F., & HIERONYMUS,A. N. Iozua Tests o f Basic Skillr. Boston: Houghton Mifflin, 1955-73. 10. OSBORN,F. Races and the future of man. In R. H. Osbotne (Ed.), Biological and social meaning o f .lace. San Francisco: Freeman, 1971. Pp. 149-157. 11. SCANNELL.D. P., et al. Tests o f Academic Progress. Boston: Houghton Mifflin, 1964-66. 12. STATE DEPARTMENTOF EDUCATION. Annual Report--Georgia Department of Education, 1970-71. Atlanta, Ga.: Author, 1971. 13. STATEDEPARTMENTOF EDUCATION. Statewide testing program, 1971-72. Atlanta, Ga.: Stare Dept. Educ., 1972. 14. THORNDIKE,R. L., & HAGEN,E. P. Cognitive Abilities Test, Multilevel Edition. Boston: Houghton Mifflin, 1973. 15. U. S. BUREAUO F CENSUS. Censrrs o f population: 1970. General population characteristics. Final Report P C ( 1 ) - B I Z , Georgia. Washington, D. C . : U. S. Gov'c Print. Off., 1971. S. G. LOS Angeles Times, Sept. 9, 1973. 16. VANDENBERG, 17. WALLER,J. H. Differential reproduction: its relation to I Q test score, education, and occupation. Soc. Biol., 1970, 18, 122-136.
JONES,
Accepted September 2, 1975.
