graph?
A. mean only
B. median only
C. range and mean
D. range and median
.
here is the item ... without the boxplot ... now, the lower point is roughly 15 ... the spot above the | is about 26 ... and the upper end point is about .. 41
of course, though the stem mentions the mode ... it is NOT an option in the choices ... so, what the heck is it doing in the stem???
the reality is ... NONE of these things (the mode certainly) can be known for sure from the boxplot ... even if we know that the | is where the median is shown ... because, all you can do is to "approximate" the values ...
so, as it stands ... there is no correct answer to this bad question ... given that the stem says "determined"
without the actual data ... and knowing the actual lower and upper scores, you can't determine the range ... without knowing the data ... you can't know the middle score
in this item ... it IS possible to "approximate" the range, to "approximate" the median, and believe it or not ... to "approximate" the mean ... since there is some skew indicated by the box part ... and, given that AND an approximation for the median ... one could thus "approximate" the mean [of course, the stem does not say the "approximate" values ... it wants you to know them for SURE]
what you CAN'T do is know anything about the mode ... of course, that is not really important here since (though in the stem) it is not in the answer possibilities
thus ... for this item you are either stuck with:
1. there are two answers that should be keyed as correct ... C and D ... allowing that "approximate" is = to "determined"
or
2. there really is NO correct answer
therefore: even if we accepted that this were an important item .. the item itself is seriously flawed ...
toss the sucker!!!
dennis roberts, penn state university
educational psychology, 8148632401
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/ ================================================================
