Anova Test Statistic Example. A two-way ANOVA is used to estimate how the mean of a quantitative variable changes according to the levels of two categorical variables. MSW Mean sum of squares within the groups.
A Tukey post-hoc test revealed significant pairwise differences between fertilizer types 3 and 2 with an average difference of 042 bushelsacre p. Value by comparing its value to distribution of test statistics under the null hypothesis Measure of how likely the test statistic value is under the null hypothesis P-value α Reject H 0 at level α P-value. Using an of 005 we have 389 see the F distribution table in Chapter 1.
The independent groups might be defined by a particular characteristic of the participants such as BMI eg underweight normal weight overweight obese or by the investigator eg randomizing participants to one of four competing treatments call.
Reporting the results of a one-way ANOVA We found a statistically-significant difference in average crop yield according to fertilizer type f29073 p. MSW Mean sum of squares within the groups. The between-sample varianceor error is the average of the square variations of each population meanfrom the mean. Consider an example with four independent groups and a continuous outcome measure.
