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1 HOW TO USE STATISTICS FOR LIBRARY DECISIONMAKING Diana Very June 27, 2011 2 MBA for Librarians: Statistics This program will demystify statistical concepts and skills and illustrate their library applications. The instructor will show how data can and should influence all areas of library operations. Learn about studies, tools and resources to assist you in comparing your data with that from other institutions. Create information, knowledge and stories from numerical and qualitative data to enhance decision making. The goal: Manage smarter. Led by Diana Very. 3 Diana Very Director of LSTA, Statistics, & Research Funding provided for this presentation by IMLS through the LSTA program grant 4 How many have never used statistics? 5 Has anyone received one of these? 100% 6 Statistics tell a story • • • • • What Where When How Why 7 What is a Statistic? • A statistic is a quantity that is calculated from a sample of data. It is used to give information about unknown values in the corresponding population. For example, the average of the data in a sample is used to give information about the overall average in the population from which that sample was drawn. • It is possible to draw more than one sample from the same population and the value of a statistic will in general vary from sample to sample. For example, the average value in a sample is a statistic. The average values in more than one sample, drawn from the same population, will not necessarily be equal. 8 Definitions • Mean • Median • Mode • Percentage Change %∆= (( − )/)*100 • Range • Sample • Standard Deviation • Target Population (Children at a Children’s Program) • Trend • Variance • Correlation 9 Example of Population, Mean, Variance, Standard Deviation • Consider a population consisting of the following eight values: 2,4,4,4,5,5,7,9 • These eight data points have the mean (average) of 5: • (2+4+4+4+5+5+7+9)/8 = 5 • To calculate the population standard deviation, first compute the difference of each data point from the mean, and square the result of each: • (2-5)2 = (-3)2 = 9 (4-5)2 = (-1)2 = 1 (4-5)2 = (-1)2 = 1 (4-5)2 = (-1)2 = 1 • (5-5)2 = (-0)2 = 0 (5-5)2 = (-0)2 = 0 (7-5)2 = (2)2 = 4 (9-5)2 = (4)2 = 16 • Next compute the average of these values, and take the square root: (9+1+1+1+0+0+4+16)/8 = 4 = variance square root of 4 is 2 = Standard deviation 10 Example of Normal Curve • This quantity is the population standard deviation; it is equal to the square root of the variance. • A slightly more complicated real life example, the average height for adult men in the United States is about 70", with a standard deviation of around 3". This means that most men (about 68%, assuming a normal distribution) have a height within 3" of the mean (67"–73") — one standard deviation — and almost all men (about 95%) have a height within 6" of the mean (64"–76") — two standard deviations. If the standard deviation were zero, then all men would be exactly 70" tall. If the standard deviation were 20", then men would have much more variable heights, with a typical range of about 50"–90". Three standard deviations account for 99.7% of the sample population being studied, assuming the distribution is normal (bell-shaped). 11 Normal Curve or Bell Curve 12 Multivariate Analysis Not as scary as it sounds Involves observation and analysis of more than one statistical variable at a time. In design and analysis, the technique is used to perform trade studies across multiple dimensions while taking into account the effects of all variables on the responses of interest. Example: During a production process, a number of different measurements such as the tensile strength, brittleness, diameter, etc. are taken on the same unit. Collectively such data are viewed as multivariate data. 13 Pearson Correlation The Pearson correlation measures the correlation or strength of linear dependence between two variables X and Y. = (−)(−) ( )( ) It returns values between +1 and −1 inclusive. 1 implies that Y increases as X increases. 0 implies that there is no linear correlation between the variables. −1 implies that Y decreases as X increases. For −1 and 1, a linear equation exists that describes the relationship between X and Y perfectly. 14 Public Library Use Determinants Total Library Reference Public Total Circulation Visits Transaction Hours Staff 18,379,134 47,155,895 39,392,010 9,513,049 882,799 2,995 9,446,298 17,856,414 47,811,748 40,852,165 8,734,545 907,316 3,105 2008 9,319,532 17,646,302 43,663,621 36,979,778 7,994,164 905,630 3,109 2007 9,098,140 17,056,943 40,816,175 35,703,912 8,275,923 896,848 3,018 2006 8,789,529 16,496,624 40,735,627 31,952,301 8,547,509 887,400 3,038 2005 8,650,046 16,041,499 41,155,342 31,557,896 8,571,452 868,892 2,796 2004 8,510,563 16,040,938 40,269,048 31,285,987 8,076,037 871,401 2,821 Mean 9,126,258 17,073,979 43,086,779 35,389,150 8,530,383 888,612 2,983 Median 9,098,140 17,056,943 41,155,342 35,703,912 8,547,509 887,400 3,018 Mode #N/A #N/A #N/A #N/A #N/A #N/A #N/A Population Total Collection 2010 10,069,700 2009 Variance Standard Deviation Correlation 541,635,247,329. 540,046.06 1,581,668,337,779. 19,057,194,894,718. 28,421,398,103,038 922,858.37 3,203,367.99 3,912,010.96 0.922 0.715 485,335,050,482.728 511,208.62 441,888,716 15,425.31 0.490 29,827 126.73 15 Public Library Use Determinants by Diana Very, 4/1/2011 • This hypothesis was based on an assumption that library users only used the libraries for new books and best sellers that are provided when the budget is available to buy them. The library materials budget was used as the independent variable assuming that the circulation was dependent on the amount available in the budget. Using the Pearson correlation coefficient of r for determining the extent to which these variables are related produced an r coefficient of -0.502 which means that there is good evidence that these variables are not correlated. • The circulation statistics are generated by the library visits, which would lend itself to project that marketing to more of the library service population would increase circulation and use of library materials rather than spending more money for new materials. When making a decision about marketing budget or materials budget, this study may prove to be helpful. 16 Where to get statistics? • Statistics are everywhere. The statistics that you want to use will depend on what decision you want to make from them. • Some questions that come up for libraries • Who are our customers? • Can we bring in more users? 17 Public Library Statistical Survey - IMLS http://harvester.census.gov/imls/publib.asp Public Libraries in the United States: Fiscal Year 2008 Release Date: June 2010 Revised Date: January 2011 http://harvester.census.gov/imls/pubs/pls/index.asp 18 Academic Library Statistical Survey • Academic Libraries: 2008 First Look • http://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2010348 • National Center for Education Statistics • FY2008 edition provides stats on 3,827 academic libraries • Circulations • Public Service Hours • Gate Count • Collection Numbers & Types • Staff 19 Public School Library/Media Center • http://nces.ed.gov/pubsearch/getpubcats.asp?sid=041# • Several reports are available at this site, but only to 2000. • Federal Libraries and Media Centers reports are also available, but not up to date. • Digest of Education Statistics, 2010 • http://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2011015 • Contains up-to-date stats for education from kindergarten through graduate school. 20 Public Library Data Service Statistical Report • The survey for 2010 data is the 23rd edition of the annual survey. • This report is created from a survey sent to 9,272 valid U.S. and Canadian libraries through web contacts. • 1,105 responded to the questionnaire. 21 Census Data • Home page of data sets and instructions • http://www.census.gov/acs/www/ • American Community Survey – Provides demographics such as population number, races, housing, education, etc., for states, counties, and municipalities • http://www.census.gov/acs/www/ • Guidance for data users – provides instruction on using the data and finding the correct data set • http://www.census.gov/acs/www/guidance_for_data_user s/guidance_main/ 22 Other Examples of Library Stats • 2011 State of America’s Libraries — ALA Releases Annual Report : http://ala.org/ala/newspresscenter/mediapresscenter/ame ricaslibraries2011/index.cfm • Library Research Service – Colorado Library Stats http://www.lrs.org/pub_stats.php • Current Look at Georgia Public Libraries FY 2010 http://www.georgialibraries.org/lib/publiclibinfo/ 23 Where to find comparative statistics • This depends on what type of comparisons you want to • • • • • make In Georgia, the library directors want to compare their system with others in Georgia In DeKalb County, Georgia, the library branch managers want to compare their branches to other libraries within the county system. The Public Library Survey from IMLS provides data for states to compare their state data with other states. Peer-to-peer comparisons; I’m ok just so I’m better than you…Oh, my! 24 Compare this year with last year • Use a trend analysis (compares different years of same statistic) for staff motivation, accountability reports, marketing and promotional activities. • Stats to Use: • Circulation • Visits • Program attendance • Genre Circulation • Library Cards • Try per capita calculations • Library Cards per capita • Program attendance per capita • Identify the % not participating. 25 A table of usable statistics Population Total Total Collection Circulation 2010 10,069,700 18,379,134 2009 9,446,298 2008 Library Visits Reference Transaction Public Hours Total Staff 47,155,895 39,392,010 9,513,049 882,799 2,995 17,856,414 47,811,748 40,852,165 8,734,545 907,316 3,105 9,319,532 17,646,302 43,663,621 36,979,778 7,994,164 905,630 3,109 2007 9,098,140 17,056,943 40,816,175 35,703,912 8,275,923 896,848 3,018 2006 8,789,529 16,496,624 40,735,627 31,952,301 8,547,509 887,400 3,038 2005 8,650,046 16,041,499 41,155,342 31,557,896 8,571,452 868,892 2,796 2004 8,510,563 16,040,938 40,269,048 31,285,987 8,076,037 871,401 2,821 26 How to make the decision – Step 1 1. What’s the situation? 4% budget cut 27 How to make the decision – Step 2 2. Decision tree • Reduce staff – already skeleton staff • Furlough staff – not fair to staff • Reduce hours – possibility • Reduce library collection budget – cut last year to nearly nothing • Reduce outreach services – agreements already in place 28 How to make the decision – Step 3 3. Justify how to reduce hours • Check into patterns of library use • Check into staff efficiencies • Check into circulation and reference use • Check into website hits and WIFI traffic 29 Group Work Name a statistic or set of statistics that will answer: • Patterns of library use • Staff efficiencies • Circulation and Reference use • Website and WIFI traffic 30 If you want to know about patterns of library use, you would collect what type of data? Reference contacts by hour 31 If you want to know about staff efficiencies, you would collect what type of data? Circulations per FTE 32 If you want to know about circulation and reference use, you would collect what type of data? Collection turnover rate (circulation/collection) Hint hint 33 If you want to know about website hits and WIFI traffic, you would collect what type of data? 34 Create a Logic Model Logic Model Template Grant Period Project Title Total Cost Project Description Resources In order to accomplish set of activities, we will need the following: Name of resources State, Federal Or Other Funding Source Other Results Anecdotal Information Exemplary Reason Activities/Methods In order to address our problem we will conduct the following activities: Name of activities Outputs We expect that these activities will produce the following evidence of service delivery Number of items Outcomes We expect changes in attitudes, behaviors, knowledge, skills resulted from this project Increased number Percentage Increase Impacts Organizational, community or procedural level changes resulted from this project. Increased Number Percentage increase 35 Example Using the Logic Model Logic Model Project Title Ourtown Summer Library Program Grant Period Total Cost 4/1/11 - 9/15/11 $1,000 per library system Project Description Ourtown public library and school library will work together to bring library activity day every Wednesday afternoon to the local mall's center staging area. Teenagers will be hired as mentors and activities will involve reading and writing stories about animals. Resources In order to accomplish Activities/Methods In order to address Outputs We expect that Outcomes We expect changes Impacts Organizational, community set of activities, we will need the following: our problem we will conduct the following activities: or underway these activities will produce the following evidence of service delivery in attitudes, behaviors, knowledge, skills resulted from this project or procedural level changes resulted from this project. Grant - LSTA Funding Publicity number of patrons served new patrons Increased attendance Staff Craft Activities Reading Stories number of computer classes Patrons comfortable with computer use Computer Training number of activities Library skills increased number of days of activities library behavioral problems decreased because of project attendance Volunteers Other Results Anecdotal Information Exemplary Reason Increased family services Improved library services 36 Pictures often say more than words 37 Tell the 2011 Clifford Presentation Story 1,518 participants 15 programs @ a Cost of 62 Per Participant http://animoto.com/play/jSIexmvTn8wimFaCnajcbw 38 Use Statistics to Make Informed Decisions • When is the busiest time at the library? • Do I need more staff to keep up? • Do we really need a new building or can we rearrange the current facility? • Should we arrange the fiction by genre or alphabetically by author? • Why is our teen collection not being used? Old collection? Hidden in the middle of the picture books? Teens don’t know about our books? • Would the community support the program if they knew the benefits? 39 Thank you!! Contact information: Diana Very Georgia Public Library Service 1800 Century Place, Ste. 150 Atlanta, GA 30345 404-235-7156 [email protected] 40 References • Standard Deviation from Wikipedia retrieved on 5/12/2011 from http://en.wikipedia.org/wiki/Standard_deviation • PLA - Public Library Data Service Statistical Report. 2010. Presented by the PLA/ALA, ordering information found at http://pla.org/ala/mgrps/divs/pla/plapublications/pl dsstatreport/index.cfm • IMLS - Public Libraries in the United States: Fiscal Year 2008. Only available on-line at http://harvester.census.gov/imls/pubs/pls/pub_det ail.asp?id=130 41 References, cont. • Smith, Mark. 1996. Collecting and using public library statistics: A how-to-do-it manual for librarians, Number 56. Neal-Schuman Publishers, Inc. • 2011 State of America’s Libraries — ALA Releases Annual Report : http://ala.org/ala/newspresscenter/mediapresscenter/ame ricaslibraries2011/index.cfm • Library Research Service - Colorado Statistics http://www.lrs.org/pub_stats.php • Multivariate Analysis Concepts, retrieved from http://support.sas.com/publishing/pubcat/chaps/56903.pdf 42 References, cont. 2 • Multivariate analysis, retrieved from Wikipedia, http://en.wikipedia.org/wiki/Multivariate_analysis • Very, Diana. 2011. Public Library Use Determinants, p 13, e-mail for copy [email protected]