BIOL 243 Lecture Notes - Lecture 10: Type I And Type Ii Errors, Null Hypothesis, Analysis Of Variance
25 Aug 2016
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If the null hypothesis is rejected, it means that one of at least one group is different from the others. Sources of variation table: residual variation: Under the null hypothesis, the ratio of the group mean square to the error mean square should be <1. Three factors: residuals are normally distributed. Skewness and kurtosis: residuals variance the same for all groups. Width is the same: y-values represent random and independent observations. Residuals are normally distributed: shapiro-wills test. If p>0. 05, we fail to reject the null hypothesis: doesn"t mean residuals are normally distributed. Residuals variance the same for all groups: bartlett"s test: H0: all groups have equal residual variance. Ha: at least two groups do not have equal residual variance. If p>0. 05, we fail to reject the null hypothesis: doesn"t mean residuals have equal variance. Evaluate whether group means differ while adjusting for the overall type i error rate. Three steps: test overall anova first.
