Degrees of Freedom and Variance Assumption
A study compared recovery times for two surgical techniques. A sample of 65 patients for the first technique had a standard deviation of 12.3 days, and a sample of 70 patients for the second technique had a standard deviation of 9.8 days. For a two-sample t-test on the difference in means, the degrees of freedom were calculated to be 123.82. This calculation implies which of the following assumptions about the population variances?
A
They are likely unequal
B
Nothing can be concluded about the variances
C
The first population has smaller variance
D
They are approximately equal
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