Therefore, it is in the librarian's interest to write reports that describe all aspects of the library's operations (and make sure they are read). Data is collected by all employees in the library in order to be able to report (annually) on all activities. The use of the intranet or the Internet in the library is an obvious example.
In addition to this, there is the problem of the enormous size of the Internet (and of the WWW) and its rapid growth (see for example Egghe (2000)). This makes it difficult to report here on the number of authors, aging of the literature, and so on. Mention the opening hours, including an indication of the use of the library at different periods (for example in the evening, to see if it is necessary to keep the library open late or not).
OPAC usage: total session time (gives the number of terminals needed), average time per session (based on this it can be concluded to what extent the OPAC is used as a bibliographic database). General: Report on information technology (IT) activities in the library (such as maintaining library websites or an online resource guide). Specify the shared use of the system (all PCs and terminals connected to the system).
The interval scale gives an indication of the differences between the data (without giving absolute data).
Descriptive statistics
The parameter b is called the slope of the straight line and a is called the intercept. Determine the "age profile" of the library using the following table of the number (y) of books of a certain age (t) (this year) (t=0 is the current year, t=1 is the previous year and soon). To test the quality of the lines obtained in the following examples and exercises, we refer the reader to Section 3.8.
We have the following data on the trend in the number of interlibrary requests for books in our library (t=1 is 1989, t=2 is 1990, and so on). Suppose we have data on the average number of books borrowed per year depending on the age of the book (expressed in years). We find a decrease in the average number of loans per year of about 0.13, which applies to the first 10 years.
Determine the bar chart and regression line for the following data, which represent the evolution of a library's budget (possibly adjusted for inflation (100=year 1991, being t=1)). This means that in 5 years (we are now in year 6) the magazine budget will represent 70% of the total budget. It is assumed that there is a linear relationship between the height of the shelf and the number of lost books.
The equation of the regression line is: number of lost books height (in cm), indeed a positive relationship between height and the number of lost books. The table below shows the number of users of a public library, grouped by municipality, and the distance between the center of the municipality and the library. The following table shows the evolution over time of the number of library users (t=0=the first year the measurements took place).
For j=25, this is called the first or lower quartile (Q1), the time needed to deliver a quarter of the ordered books. In any case, all these percentiles Pj give information about the (ir)regularity of the deliveries. We hope that the reader is now convinced of the power of percentiles in calculating the (ir)regularity of data.
Now we calculate cumulative partial amounts, that is the number of loans in the highest category, the sum of the first and the second category, the sum of the first three categories and so on. In this case one calculates the coefficient of variation - the ratio of the standard deviation and the mean.
Inferential statistics
N≥30 is required for a good approximation of the distribution of the normal distribution in the central limit theorem (see the beginning of this section). Is the average number of books received by corporate libraries significantly different from the average for all members of the network. Other values can be found in the standard normal distribution table (not used here).
This technique of determining confidence intervals for the population mean (based on a sample with parameters N and s) is one of the highlights of Part 3 and is often used in reports. A sample of 101 books in the library gives an average reference list length of 83.3 references (so =83.3). So we are 95% confident that between 80% and 86% of the cards were entered into the automated system.
It is increasingly necessary to have an idea of the overlap between your library and another (or another group of libraries). The right-hand side of this equation is the quotient of the number of books belonging to both libraries and the number of books in library A. So the overlap is a fraction: that is, the fraction of books in A that also belong to B.
This score is considered too low and we are working on the quality of the service (for example more staff, friendlier service and so on). A librarian examines the circulation activity (during a certain year) of the books in the library written in French. A sample of size N1=1075 in the circulation data shows that these books make up 11% of the total number of loans.
If we require the total length of the 95% confidence interval to be less than 0.2, then we have A sample of 100 books taken from a section of the library shows that 3% of the books are lost. Fractions of library books with n authors (n optionally further subdivided by language and age of the book and whether or not the book is in the library's automated catalog.
We checked the fractions of the books in the library with or more authors. We assume that the delivery times for books from a supplier are independent of the delivery times for interlibrary ordered books.
Conclusion
Logic of calculations
Basic arithmetic on pocket calculators
List of notation
Bibliography
UNESCO Questionnaire on Libraries Statistics: Part II: Libraries of Higher Education Institutions and School Libraries in 1987, Paris.
Subject Index
