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help for ^modt^ and ^modti^					  STB-28: sg43
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Brownie et al.'s modified t-test
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        ^modt^ var1 ^=^ var2 [ ^if^ exp ] [ ^in^ range ]

        ^modt^ var [ ^if^ exp ] [ ^in^ range ] ^, b^y^(^groupvar^)^

        ^modti^ n1 mean1 sd1 n2 mean2


Description
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^modt^ performs Brownie et al.'s modified t-test.  This test is primarily useful
for comparing the means of two groups where one group is a control group, and
it is expected that the variance of the treatment group will be larger than the
variance of the control group.  In the first syntax, the control should be
entered as ^var1^.  In the second syntax, the control group should have the lower
value of ^groupvar^.

^modti^ is the immediate version of the command.  In this version, ^n1^, ^mean1^, and
^sd1^ are the number of observations, mean, and standard deviation of the control
group.  ^n2^ and ^mean2^ are the number of observations and the mean of the treat-
ment group.  The test does not require the dispersion of the treatment group.


Options
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^by(^groupvar^)^ specifies the variable that distinguishes the control from the
    treatment group.  The control is assumed to be identified by the lower of
    the two values in ^groupvar^.


Example
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 . ^modt mpg, by(foreign)^


Author
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        Richard Goldstein, Qualitas Inc.
        richgold@@netcom.com


Also see
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    STB:  STB-28 sg43