d johnson: I’m well aware of the library ROI calculators (they’ve been around for years, all originating from one source) and think they’re great. But they’re for individual use. I’m looking at broader trends.

Steve: If you’ve read any of my research work, you know that I’m always 100% explicit about my assumptions and methods. That’s been true for years. (If you haven’t read any of my earlier work, I’m a little surprised that you’re commenting here.) (See below.)

Others: Thanks–and Crystal, I think I hear one reason I think this might be valuable and different: I really, truly, completely am NOT interested in setting up another list of “here are the GREAT libraries.”

1. I’m not claiming that what I’m doing is “more valid”–but individual libraries and states might find it additionally valuable. I do not in any way intend to replace state ROI studies.

2. My model is deliberately simple, conservative, and designed to return a minimum value, based only on countables as reported to IMLS. The model will be stated in full as part of the book.

3. To me, it’s not at all obvious that well-funded libraries continue to return equivalent value for additional dollars spent, and I don’t think that’s obvious to a typical skeptical user either. Why is it obvious that a library spending $50 per capita will offer twice as much value to the average user as one spending $25 per capita? I certainly don’t assume the Pentagon’s $600 hammers are 30 times as good as ordinary $20 hammers…

4. The key difference between the book I’m considering doing and all of the ROI studies I’ve looked at: I’m not just offering One Big Number, but ranges and correlations–so, say, a library serving 25,000 people with $30 per capita expenditures in Colorado can compare itself to other libraries in the same size range, funding range, or state (and broader size range), and have some evidence that $40 per capita funding would yield worthwhile additional value. (Compare itself: Not because it would be named in the book–no library will be called out by name–but because any library should know its reported numbers and can repeat the calculation I’ve done. If a library doesn’t, email to me will return the appropriate line of the spreadsheet, for the library’s internal use, since I *can* go back to names through a two-step process.)

It also seems like a no-brainer premise to say that “libraries that are better funded provide better service.” One of the pitfalls of using data collected for one purpose to apply to a different purpose is that it requires numerous questionable assumptions to make the numbers meaningful. How would this data be more valid or more valuable than the results from several states that conducted their own ROI study within the past few years? The 21st Century Library is More: