t Test Assumptions: Paired/dependent/matched Samples: two matched or paired samples data from populations are assumed to approximate a normal distribution Variance for both samples are approximately equal Observations must be independent of each other outliers Max value 75th percentile Median 25th percentile Min value

One-tailed vs. Two-tailed test of significance. With a two-tailed test of significance (at the .05 level), the alpha is split so that both directions can be covered. With a one-tailed test of significance the alpha is not split and is applied to one direction – with a one-tailed test you are testing for significance in one direction and disregarding the possibility of significance in the other direction. The one-tailed test is more likely (more powerful) in finding significance.

Group A – McDonald’s Coffee Within Group Variance Sampling Error Variance Mean

Group B – Tim Horton’s Coffee Within Group Variance Sampling Error Variance Mean

Group A – McDonald’s Coffee Group B – Tim Horton’s Coffee Mean Mean

Group B – Tim Horton’s Coffee Group A – McDonald’s Coffee Mean Mean Between Group Variance

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