Statistics for People Who (Think They) Hate Statistics

by Neil J. Salkind

Make sure that the instructions are standardized and clear across all settings in which the test is administered. Increase the number of items or observations because the more questions on a test, the more opportunities for that randomness in responses to cancel itself out. Typically, the longer the test, the more reliable. Delete unclear items because some people will respond in one way and others will respond in a different fashion, regardless of their knowledge or ability level or individual traits. For an achievement test especially (such as a spelling or history test), make sure that the questions aren’t too hard or too easy. You want there to be some variability across people, so their true, typical scores have a chance to appear. Minimize the unpredictable effects of external events on test performance. For example, if a particularly important event, such as Mardi Gras or graduation, occurs near the time of testing, you might postpone an assessment.