Friday, 15 June 2012

THE OLD PHILOSOPHER LEARNS A NEW TRICK OR TWO

I have often remarked that I do not consider myself a scholar.  It goes without saying that I also do not consider myself a research scientist.  But my lack of research credentials was brought home to me rather abruptly by Dania Francis, the young advanced doctoral student whom I recruited, at the suggestion of the head of the Spencer Foundation, to assist me with the formulation of what is apparently called a “research protocol” for my new  project at Bennett.

I had decided to select sixty of the incoming one hundred eighty-three Bennett Freshwomen for the Pilot Program I shall be running in AY 2012-2013.  For various reasons, I wanted a representative sample of students, as determined both by their high school GPS’s [that is “grade point average” for my foreign readers] and by their status as either in-state North Carolina students or out-of-state students. 

The Excel spreadsheet of the incoming students provided to me by the “Office of Enrolment Management” is organized in descending order by GPA, so, since I was selecting a third of the class for my Pilot Program, I thought the cool way to choose them would be simply to go down the list, tagging every fourth name.  This produced a representative selection of GPA’s and, as I anticipated, close to a representative sample by geographic origin.  Pretty good, yes?  I then divided the sixty students thus selected into ten groups by simply opening a new field in the spreadsheet called “Group,” and then going down the list of sixty students [still arranged, of course, by GPA] and marking the fields numerically, 1 through 10, in order, thus producing ten groups, each of which had a range of GPA’s.  I checked, and they also had a scattering of in-state and out-of-state students.  Along about now, I was feeling pretty good about myself, thinking that I could do this without the help of a graduate student!

With mock modesty, I explained all of this to Dania, expecting her to exclaim, “But that is exactly the way it should have been done!”  Fat chance.  She looked at what I had done and said quietly, “I think you should choose the students randomly.”  “But,” I replied, “My way has produced a selection that almost perfectly mirrors the entire class.”  “Yes,” she replied, “but there may be hidden variables.  I think the Spencer Foundation would prefer a random selection.”

Well, all of this was in aid of getting money from the Spencer, and my ego is not so large as to stand in the way of a grant, so I said, “How would you do that?”  “Very simple,” she said [rather like explaining rain to a child], “we just assign them numbers 1 through 183, and then generate a random number sequence that selects sixty of them.  Then we do the same thing to group them in ten groups of six each”  [I hope I have that right.]  She drove back to Boston from Amherst, and had it all done by the next day.

I reported all of this to Mike McPherson, President of the Spencer.  Here is his reply:  Sounds great. It's a good sign that she immediately recognized the need to use random assignment, since that option is available.”

Pretty clearly, I have a lot to learn.