Chapter 7. Two-Way ANOVA

  • 7.1 Introduction 95

  • 7.2 Synopsis 95

  • 7.3 Examples 98

  • 7.4 Details & Notes 119

7.1 Introduction

The two-way ANOVA is a method for simultaneously analyzing two factors that affect a response. As in the one-way ANOVA, there is a group effect, such as treatment group or dose level. The two-way ANOVA also includes another identifiable source of variation called a blocking factor, whose variation can be separated from the error variation to give more precise group comparisons. For this reason, the two-way ANOVA layout is sometimes called a 'randomized block design'.

Because clinical studies often use factors such as study center, gender, diagnostic group, or disease severity as a stratification or blocking factor, the two-way ANOVA ...

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