Working with Library Statistics

This page contains a list of items and services you may include in your library practice. For each item, a definition is provided and a data source is identified for collecting appropriate statistics. Issues that you may need to think about when you are planning your data collection are identified under the "Considerations" heading. Level of difficulty for is given for each item or service in this collection.

This page is intended to be a general guide for the collection of meaningful statistics in your library evaluation program. Evaluate your own programs and situations and make needed adjustments to reflect your unique library.

Definition: Print and e-books used in the library, checked out by users, or accessed online. Consider Table of Contents, Chapters or Pages viewed.

Data Source: Count of books shelved including those returned from checkout and those used in the library and left on tables, chairs, etc.


  • Ask users not to reshelve their own books OR ignore items used and reshelved by users
  • Someone has to count - while shelving or by bringing all materials to a central place, counting and recording in a log

Difficulty Level for Collection: Easy


Definition: E-books are accessed online. Determine what data your vendors provide and try to be consistent across vendors. Consider Table of Contents, Chapters or Pages viewed.

Source of Data: E-Books: E-book use from vendors; internal tracking systems for linking to resources, i.e., Serials Solutions or other link resolvers, proxy servers such as Ezproxy.

Considerations: What is the vendor providing? Can it be retrieved online by the librarian? Is it provided in a spreadsheet, text document, paper document? Is the information consistent from vendor to vendor - such as hits to TOC, page hits in the book, image hits, chapter hits, title, by title use within a resource such as Stat Ref, MDConsult, etc.

Difficulty Level for Collection: Complex.

Definition: Use shelving statistics for print journals and decide what each item shelved represents.

Source of Data: Count of items shelved (this will include both circulated and in house use) or just count circulations (will not include what was used in the library but not checked out).

Considerations: You might assume that each physical item represents, on average, one article read. Users might read more than one article or none, looking only at the table of contents or index. You decide what the average is per physical item. You might want to conduct a brief survey, asking users how many articles they read for each item taken off the shelf. Use an average of their responses.

Difficulty Level for Collection:

  • Easy: Collect all materials on a book cart, count, record then reshelve.
  • Moderate: If you want to verify the number of articles read or used. Do occasional sampling, asking users how many articles they have read in whatever they return to the library and/or what they have near them in the library.


Definition: Vendors provide use statistics for e-journals. As for print journals, decide what that use represents. If it's hits on Tables of Contents, or hits per issue, that could represent, on average, one article read per hit. If the vendor supplies article level statistics, you can use that. You may need to adjust different vendor stats so the common denominator is articles read.

Source of Data:

  • Use ScholarlyStats (Swets service) or other Vendor supplied data.
  • You might be able to capture clicks to e-journals through your catalog. This requires a competent programmer to create a program to capture the URL clicked.

Considerations: Vendor statistics may not adhere to the Counter standards; provides standardized, consolidated reports for Swets customers. You might have to collect stats from each resource and determine a way to standardize the information; you may have to devise a factor that multiplies or divides statistics so they represent the same information from vendor to vendor.

If one report provides sessions, one provides Table of Contents hits, one provides full text hits and one provides pages viewed how do you make each represent what you want - articles read? Being conservative you count the first three types of stats as one article read and perhaps divide the page views by an average number of pages per article to get the number of articles for that set.

Difficulty Level for Collection: Moderate to Complex. Counting use is difficult until the exact method is established. Establishing what and how to count is difficult and takes up a huge amount of time, especially if you have more than one vendor.

Document Delivery

Definition: Document delivery includes items supplied by other libraries for your primary and affiliated users, and items copied or delivered from your library collection to your primary and affiliated users. Do not count items sent to other libraries.

Source of Data: Library records for items obtained from other libraries and copies of articles supplied from your collection.

Difficulty Level for Collection: Easy

Value or Benefit:

  • Demonstrates the ability to provide same access as larger or academic libraries.
  • DOCLINE system provides quarterly and annual borrowing and lending statistics.

Reference Questions

Definition: A reference question is an information request that requires knowledge, use, recommendations, interpretation, or instruction in the use of one or more information sources. Include questions that come from all sources: reference desk, email, telephone, "Ask a Librarian" button on webpage. Count mediated searches as specific requests under the Mediated searches line. Do not include directional questions.

Source of Data:

  • Tick marks recorded for questions answered or other record keeping method
  • Determine the average amount of time, in hours or tenths of hours, spent on a question
  • Determine the likely hourly rate an information broker would charge
  • Multiply the hourly rate times the average time to answer a question. That amount becomes the cost of reference service (the second box).
  • Enter the number of reference questions, tab to the rate and enter what you figured above.


  • Do you want to differentiate by type of question, resources used to answer, average amount of time spent? The retail value calculator default is 30 minutes @ $70/hour. The rate is what an information broker might charge - NOT the librarian's salary.
  • You might want to weight your stats - so 50 reference questions per month take, on average, 1.5 hours each to answer (75 hours) and 100 questions take 10 minutes each (16.6 hours). 150 questions took a total of 91.6 hours. Divided by 150 questions, the average time for all reference questions is 37 minutes.
  • If a broker fee is $150/hour your cost for reference questions would be .61 hours per question *150, or $92.50 per question.

Difficulty Level for Collection: Moderate (for the math to determine the cost per reference question)

Mediated Searches

Definition: Include database searches completed at the specific request of a user. Database searches performed in the process of answering a reference question are counted under Reference Questions answered.

Source of Data: Your records of search requests filled. You also need to track the hours per search.


  • Calculate the average time you spend on searches. If you do 25 searches per month, and it takes you a total of 22.5 hours, the average search takes .9 hours. If an information broker charges $150/hour, the value of each search is 150 * .9 or $135.
  • Enter the number of searches in the first box (retail value calculator), enter the charge in the next box.

NOTE: This is not for searches done by users on databases you subscribe to. If you want to include this service enter it in one of the lines provided for additional services/resources.

For database valuation:

  • What statistics are provided by vendors - Sessions? Searches? You need to decide what a session represents or how many sessions are represented by the number of searches done. Add the cost of all databases subscribed to, divide by the number of databases to get an average database cost.
  • You could choose to provide information for only your two or three most popular or most expensive databases.
  • Should you include Ovid statistics since PubMed is free and your users could use PubMed as a substitute for Ovid if the library weren't there?

Difficulty Level for Collection: Moderate (for the math to determine the cost per search question and the extra time to record how long each search took.

Class Contact Hours

Definition: Multiply the number of classes taught times the number of hours each class lasted times the number of students in each class. Classes taught over several sessions are considered one class that lasted the total hours of the combined sessions. Example: 1 class, 2 hours per week for 4 weeks, with 5 students totals 40 class contact hours. You are determining what each student would pay for a class of x total hours. This is an 8 hour class. It could be taught in one day, two days or two hours a week for 4 week.

Source of Data: Record the of length of each class and the number of students in each class. Do not include your preparation or teaching time. The value is what the student would pay for a class of that length offered by another institution.

Considerations: Some classes, such as PubMed, may not be available elsewhere, or may be available as free online tutorials. Do you want to include or exclude these?

Difficulty Level for Collection: Moderate, depending on how the availability of information about the cost of alternatives.

Audio-Visuals (Used or Borrowed)

Definition: Because AVs are often very expensive and more difficult to find you may want to value them separately from other formats.

Source of Data: Library use records

Considerations: Determine the average cost of AVs purchased by the library. You may want to consider different formats separately, or decide whether to include only items acquired in the last X years that are likely to be available elsewhere and at what cost.

Difficulty Level for Collection: Easy

Self Service Photocopies

Definition: Use the number of photocopies made by users not by library staff.

Source of Data: Photocopy machine counters. You may need to begin keeping a monthly or quarterly record of copies made.

Considerations: Identify alternatives - the public library, FedEx offices, business supplies stores and use the least expensive per page cost.

Difficulty Level for Collection: Easy. Call local sources and ask their per page photocopy cost for black and white and/or color depending on the service you have available for your users.

Meeting Room Use

Definition: Some organizations charge back for using rooms and other facilities. Skip this service if your organization does not charge or if the library has no role in room reservations/use.

Source of Data: Records of meeting room use. You may need to begin retaining records if you haven't done so routinely.

Considerations: What alternatives are there for your users? If the library were gone would the rooms still be available, just administered by a different group in the institution? Would users have to find outside space? If so, what are the possibilities and what is the cost to use that space? Consider your public library, community centers, local universities.

Difficulty Level for Collection: Moderate

Hours of computer use (library catalog, Internet and MS Word, etc.)

Definition: Often the library is the only place where staff have access to a computer with general productivity software and/or for internet searches.

Source of Data: Multiply the number of hours per week computers in the library are available to users times 52 weeks. Estimate the percentage of time the computers are actually in use and multiple the total hours per year by that. Example: Library open 40 hours per week, 3 computers for users are in use 50% of the time. Total computer use is 40*52*3*.50 = 3120 hours. If your library is available 24/7 with card or key access estimate use or conduct an occasional survey asking users to note date/time they used computers when the library is closed.

Considerations: Check with the public library and stores such as FedEx to determine alternatives for computer and internet access. If your institution allows the same level of access in offices and/or on patient units what makes computer access in the library an added benefit? If it's the only place where electronic resources are available then alternatives will not replace your computers. If similar access is not available at their workstation, users will benefit from the computers in the library.

Difficulty Level for Collection: Moderate for collecting hours of use


Definition: Usually a collection of links to published resources, organized by multiple fields and searched using Boolean logic.

Source of Data: Vendor statistics

Considerations: It is difficult to determine a single statistic that applies to all databases or a single, average price that reflects the replacement cost of the average database. Some are available through individual subscription, some through purchase of a CD, some by payment of a per use charge and some only through an institutional subscription. You might group those databases that have similar characteristics - use statistics based on searches or sessions and similar alternative payment options. If a database is available free you may need another justification for considering it in this calculator. For instance, Ovid Medline can be freely replaced by PubMed so you may need an intangible, such as more effective search mechanisms, to justify comparing the cost to the alternative. UpToDate is available by individual subsription at three different rates. Which rate do you choose - or do you average based on your user population? Or take the least expensive option (cost for Residents)?

Difficulty Level for Collection: Complex

Definition: Searching for subject specific information on various search engines on the internet.

Source of Data:

  • Tick marks recorded for questions answered or other record keeping method
  • Determine the average amount of time, in hours or tenths of hours, spent on a question
  • Determine the likely hourly rate an information broker would charge
  • Multiply the hourly rate times the average time to answer a question

Considerations: See Reference Questions

Difficulty Level for Collection: Moderate due to determination of time spent, difficulty of search and determination of comparable cost of Information Broker.

Contact Barb Jones, Liaison for Advocacy, with questions or comments or for assistance in developing advocacy programs.