Unit 4: Interval & Ratio Tests
|• The null hypothesis is the hypothesis that sample observations results purely from chance. |
• The alternative hypothesis is the hypothesis that sample observations are influenced from some non-random cause, and that there is significance in the population.
4.2 Need for Statistical Tests
|Statistical tests indicate whether observations are significant or due to sample error. (p < .05) indicates that the probability of error is less than 5%, or that the results are significant at the .05 level.|
4.3 The T-Test
|The t-test is used to compare the means of two groups. If t is greater than the critical value, reject the null hypothesis and assume the difference between the group means is significant. |
Use the formula below to calculate t. Find the critical value from the t-table.
4.4 One-way Analysis of Variance (ANOVA)
|Use the ANOVA worksheet to calculate the f-statistic. Look up the critical value for f in the f-table (on the back of the worksheet). If f is equal to or greater than the critical value, then reject the null hypothesis.|
4.5 Post-hoc Tests
|Post-hoc tests indicate which group means are statistically significantly different. |
Tukey’s HSD (honestly significant difference) Test:
• Find q in the q-table.
• Use the formula below for HSD.
T-Test & ANOVA
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