At 01:35 PM 11/28/01 -0600, jim clark wrote: >Hi > >On Tue, 27 Nov 2001, Thom Baguley wrote: > > I'd argue that they probably aren't that independent. If I ask three > > questions all involving simple algebra and a student doesn't > > understand simple algebra they'll probably get all three wrong. In > > my experience most statistics exams are better represented by a > > bimodal (possibly a mix of two skewed normals) than a normal > > distribution. Essay based exams tend to end up with a more unimodal > > distribution (though usually still skewed). > >The distribution of grades will depend on the distribution of >difficulties of the items, one of the elements examined by >psychometrists in the development of professional-quality >assessments.
well, not exactly ... it depends on a joint function of how hard items turn OUT to be AND, where i set the cut scores for grades items can be real difficult ... but still exhibit some spread .. hence my distribution of grades may or may not exhibit some spread depending on where i set the A, B, etc. points item difficulties will determine (usually) the general SHAPE of the distribution of SCORES ... but grades are on top of scores and do NOT have to conform to the shape of the distribution of scores unless your semantics was equating the term grades with the term scores ... _________________________________________________________ dennis roberts, educational psychology, penn state university 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] http://roberts.ed.psu.edu/users/droberts/drober~1.htm ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================
