Letters PERIODICAL PRICES U.S. MEDICAL TITLES
To the Editor: The combined American periodical cost indexes, mentioned in my recent letter [1], appeared in the August issue of Library Journal (LJ) this year. Publication plans for LJ were adjusted because of the lateness of the American Library Association conference. Presumably the publication schedule will revert to normal next year and the full index information will be in the July LJ.
and first-class service. The Z-score of 2.588 indicates that the probability that this difference occurred by chance is less than 0.0048. TABLE I OUR LIBRARY'S SUCCESS RATE OF EXCHANGE ACTIVITIES
Sample size: Items ordered: Items received: Percent received: Z = 2.588
Third class
First class
183 3337 1355 40.61
460 5377 2792 51.92
JAMES W. BARRY Tucson, Arizona
If our success rate was significantly improved by subscribing to the first-class mail service, we then wondered if this also held true for other liREFERENCE 1. BARRY, JAMES W. Periodical prices: U.S. medical braries requesting exchange materials from us. To titles. Bull. Med. Libr. Assoc. 64: 335, July 1976. test this hypothesis, we collected data on the success rates that the requesting libraries achieved from our Exchange List No. 10178, published in EVALUATION OF FIRST-CLASS MAIL SERVICE OF July 1976. Table 2 compares these results. Once THE MLA EXCHANGE again, statistical tests showed that there was a highly significant difference between the success To the Editor: rates under the two types of mail service. The ZWe recently conducted an informal survey of score of 2.938 indicates that the probability that the MLA institutional members within a twenty- this difference occurred by chance is less than five-mile radius of our library to see if there was a 0.0016. substantial delivery lag between the two types of TABLE 2 mail service offered by the MLA Exchange. Our SUCCESS RATE OF OTHER LIBRARIES FROM OUR survey revealed that the two libraries subscribing EXCHANGE LIST to the first-class service for twenty-three dollars a First class Third class year were receiving their MLA Exchange lists each month an average of twelve days sooner than 85 21 Sample size: the four libraries accepting the no-cost, third-class 244 85 Items ordered: service. This led us to wonder whether the "first36 37 Items received: class libraries" were achieving a significantly 14.75 43.53 Percent received: higher success rate in their exchange activities Z = 2.938 than the "third-class libraries." To test our hypothesis, we collected data over a Therefore, librarians who want to receive the period of fifteen months. During the first four greatest possible benefit for their investment in months, we received our exchange lists by third- exchange activities should definitely invest in the class mail. We then subscribed to the first-class first-class service. This, of course, assumes that liservice for the remaining eleven months. As each brarians will process their lists and send out their exchange shipment arrived, we made a notation of orders as soon as possible after the exchange lists the ratio of received items to ordered items (see are received, for as the days pass, the advantage Table 1). of the first-class service quickly vanishes. When we submitted the data in Table I to a "Difference-between-two-sample-proportions" test, we found that there was a highly significant difference between the success rates of third-class Bull. Med. Libr. Assoc. 65(l)January 1977
HARRIET H. CARTER
The Fels Research Institute Yellow Springs, Ohio
71
To the Editor: The combined American periodical cost indexes, mentioned in my recent letter [1], appeared in the August issue of Library Journal (LJ) this year. Publication plans for LJ were adjusted because of the lateness of the American Library Association conference. Presumably the publication schedule will revert to normal next year and the full index information will be in the July LJ.
and first-class service. The Z-score of 2.588 indicates that the probability that this difference occurred by chance is less than 0.0048. TABLE I OUR LIBRARY'S SUCCESS RATE OF EXCHANGE ACTIVITIES
Sample size: Items ordered: Items received: Percent received: Z = 2.588
Third class
First class
183 3337 1355 40.61
460 5377 2792 51.92
JAMES W. BARRY Tucson, Arizona
If our success rate was significantly improved by subscribing to the first-class mail service, we then wondered if this also held true for other liREFERENCE 1. BARRY, JAMES W. Periodical prices: U.S. medical braries requesting exchange materials from us. To titles. Bull. Med. Libr. Assoc. 64: 335, July 1976. test this hypothesis, we collected data on the success rates that the requesting libraries achieved from our Exchange List No. 10178, published in EVALUATION OF FIRST-CLASS MAIL SERVICE OF July 1976. Table 2 compares these results. Once THE MLA EXCHANGE again, statistical tests showed that there was a highly significant difference between the success To the Editor: rates under the two types of mail service. The ZWe recently conducted an informal survey of score of 2.938 indicates that the probability that the MLA institutional members within a twenty- this difference occurred by chance is less than five-mile radius of our library to see if there was a 0.0016. substantial delivery lag between the two types of TABLE 2 mail service offered by the MLA Exchange. Our SUCCESS RATE OF OTHER LIBRARIES FROM OUR survey revealed that the two libraries subscribing EXCHANGE LIST to the first-class service for twenty-three dollars a First class Third class year were receiving their MLA Exchange lists each month an average of twelve days sooner than 85 21 Sample size: the four libraries accepting the no-cost, third-class 244 85 Items ordered: service. This led us to wonder whether the "first36 37 Items received: class libraries" were achieving a significantly 14.75 43.53 Percent received: higher success rate in their exchange activities Z = 2.938 than the "third-class libraries." To test our hypothesis, we collected data over a Therefore, librarians who want to receive the period of fifteen months. During the first four greatest possible benefit for their investment in months, we received our exchange lists by third- exchange activities should definitely invest in the class mail. We then subscribed to the first-class first-class service. This, of course, assumes that liservice for the remaining eleven months. As each brarians will process their lists and send out their exchange shipment arrived, we made a notation of orders as soon as possible after the exchange lists the ratio of received items to ordered items (see are received, for as the days pass, the advantage Table 1). of the first-class service quickly vanishes. When we submitted the data in Table I to a "Difference-between-two-sample-proportions" test, we found that there was a highly significant difference between the success rates of third-class Bull. Med. Libr. Assoc. 65(l)January 1977
HARRIET H. CARTER
The Fels Research Institute Yellow Springs, Ohio
71
