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Mindfulness Control
Condition Stress (X 1 ) (X 1 - M) (X 1 - M) 2 Condition Stress (X 2 ) (X 2 - M) (X 2 - M) 2
1 2.98 0.42 0.18 41 3.82 0.67 0.45
2 4.68 2.12 4.49 42 4.18 1.03 1.06
3 2.52 −0.04 0.00 43 4.03 0.88 0.77
       
40 3.17 0.61 80 3.69 0.54 0.29
N 40 df 1 39 N 40 df 2 39
2.56 1.08 3.148 0.93
M 1 SD 1 M 2 SD 1
Estimated Population S 2 SD 2 Estimated Population S 2 SD 2
1 2
Variance from the Variance from the
Sample S 2 1 1.17 Sample S 2 2 0.86
df Total df ++ df
1 2
78
df Total
Pooled Estimate of the Population S Pooled df 1 S ) ++ df 2 2
2
2
Variance df Total ( 1 df Total ( S )
2
S Pooled 1.015
2
Variance of the S 2 S 2 / N Variance of the S 2 S 2 / N
M 1 Pooled 1 M 2 Pooled 2
Distribution Distribution of Means
2
2
of Means S M 1 0.02538 S M 2 0.02538
2
2
2
Comparison Distribution: S Difference S M 1 ++ S M 2
Distribution of Differences S Difference 0.05076
2
Between Means
2
S Difference S Difference
S 0.2253
Difference
t-Score t ( M – M )/ S Difference
1
2
t −2.61
Figure 10.10 Computations for t-Test for Two Independent Samples
associated variances. Thus, the variance for the mindfulness condition
2
2
is 1.08 or 1.17, and the variance for the control condition is 0.93 or
0.86. Now, we want to pool these together. To pool these together,
we use the formula, S 2 Pooled == (df / df Total )(S 1 2 ) ++ (df / df Total )(S 2 2 ).
1
2
Granted, when both groups have the same N, pooling in this way
isn’t technically necessary. However, we’re going to stick with this

366 S TATIS TI c S F OR R ESEAR c H

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