8-25 A Test for the Difference between Two Population Means: Assuming Equal Population Variances.
{"Image DocumentName": "8-25A Test for the Difference between Two Population Means: Assuming Equal Population Variances.", "Image ImageDescription": "If we might assume that the population variances \uf07312 and \uf07322 are equal (even though unknown), then the two sample variances, s12 and s22, provide two separate estimators of the common population variance. Combining the two separate estimates into a pooled estimate should give us a better estimate than either sample variance by itself. x1.   } Deviation from the mean. One for each sample data point. Sample 1. From sample 1 we get the estimate s12 with (n1-1) degrees of freedom. Deviation from the mean. One for each sample data point.   x2. } Sample 2. From sample 2 we get the estimate s22 with (n2-1) degrees of freedom. From both samples together we get a pooled estimate, sp2 , with (n1-1) + (n2-1) = (n1+ n2 -2) total degrees of freedom.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}