1. If you assume all ratings of -1, total is -30. So any symptom more -ve than that needs a rating -2. i.e., -33.. just one symptom.
2. symptom with lowest sd is T. By the meaning of sd, lowest sd values are closest to mean.
How to solve? Are there any shortcuts to take when faced with a problem like this?
30 hospital patients who had been treated for the same illness were given a new treatment in a research study. They were asked to evaluate whether five symptoms, H, L, P, T, and V, were made better or worse by the new treatment compared to the old treatment. For each symptom, each patient used one of five ratings:
0:neither better or worse
For each symptom, the sum and standard deviation of the ratings are listed below:
Symptom / Sum of 30 ratings / s.d. of 30 ratings
H / 12 / 1.40
L / 35 / 0.69
P / -33 / 0.79
T / -26 / 0.43
V / 2 / 0.89
1) Based on the sums of the ratings alone, how many of the symptoms must have had at least one rating of -2?
A)None B)One C)Two D)Three E)Four
2) For which symptoms are the ratings closest to the arithmetic mean for that symptom, as measured by the s.d. of its ratings?
Any help is appreciated...thanx!
Last edited by jwes; 08-17-2008 at 02:11 AM.
Answer for firswt questions is One
i.e sum of rating is -33
coz if we have 26 -1 votes minimum of three -2 is a must
-26 -2 -2 -2 -1=-33
the rest options like 12 can be any may or may not contain a -2 rating
-33,35,-26 all may or may not have -2 rating but -36 should have a -2 atleast
and regarding second question not clear yet
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