
Command: TwoSampleTTest
Description: This command compares the population means of two populations when population standard deviation is unknown. A
t = |
| o1 – o2 |
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| 2 | 2 | ||
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| n1 |
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| n2 |
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o1 : mean of sample 1 data
o2 : mean of sample 2 data
n2 : size of sample 2
This formula is applicable when the population standard deviations of the two populations are not equal. The denominator is different when the population standard deviations are equal.
The t distribution degrees of freedom df and
When the two population standard deviations are equal (pooled)
df = n1 + n2 – 2
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n1 | + n2 – 2 | ||||
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When the two population standard deviations are not equal (not pooled)
df =
1
C2
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| x1σ | |
C = |
| n1 |
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n1n2
Command Syntax
Syntax 1 (list format)
“∝1 condition”, List(1), List(2), Freq(1) (or 1), Freq(2) (or 1), Pooled condition (On or Off)
*“Freq” can be omitted. Doing so sets “1” for “Freq”.
*“Pooled” can be omitted. Doing so sets “Off” for “Pooled”.
Syntax 2 (parameter format)
“∝1 condition”, o1 value,
* “Pooled” can be omitted. Doing so sets “Off” for “Pooled”.
20021201