This reminds me of a study in which students freshman chemistry (?) at another university were given a pretest and posttest to see how much they learned over the semester. For one of the sections, the mean increase was actually negative! OOPS!
Rich Einsporn U. of Akron Jay Warner wrote: > --- snip, snip --- > > Next, is it reasonable for some students to do less well on the second test > than the first? Of course it is possible. maybe the kid had a bad day the > second time, or was coming down with a bit of flu. These would be reasons why > the "true" score was less the second time. > > Also, the score on the test only reflects the capabilities of the student > (let's avoid the long tangent argument here, OK?); there is a "measurement > error" involved. Who knows, maybe they cribbed answers from the proctor on the > first test! The measurement error can be positive or negative. If it happens > to be larger than the "true" amount of gain by a student, we could wind up with > a negative measured gain. > > Your tests could well measure what _average_ gain your students achieved. With > enough data (numbers of kids) it could say what the average gain was with some > accuracy (small confidence interval for the estimate of the mean gain). . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
