Chapter 14: Two-Factor ANOVA (Independent Measures) To make the transition between one-way designs and two-way designs, let’s start with a one-way design and then extend it to a two-way design. Suppose that you are interested in the effects of a particular study strategy on memory for verbal information. You decide to use two different study strategies: Repetition and Imagery. Your participants are shown a list of 30 words, one at a time. One half of your participants is told to repeat each word over and over as it appears. The other half of your participants is told to create an image of each word as it appears. [The independent variable, or factor, would then be the study strategy.] After presenting the list, you provide a distractor task (e.g., count backward from 571 by threes), then ask the participants to write down as many of the words as they can remember. [The dependent variable would then be the number of words recalled.] For this factor, your null hypothesis would be: H0: Repetition = Imagery Compute a one-way ANOVA on these data: Repetition Imagery Sum (T) SS Males 14 19 175 258.47 13 24 10 25 11 20 17 22 Females 13 19 185 234.46 15 23 12 24 14 25 16 24 Sum (T) 135 225 360 (G) = 6978 X2 42.5 50.5 SS Source SS df MS F Strategy Within (Error) Total Now, suppose that you included an number of men and women in the experiment. In fact, the first 5 participants in each group were males and the second 5 participants were females. You could now reanalyze the data as a one-way ANOVA to look at the impact of gender. Thus, you would ignore the effects of strategy and analyze only for the impact of
Chapter 14: Two-Factor ANOVA (Independent Measures) To make the transition between one-way designs and two-way designs, let’s start with a one-way design and then extend it to a two-way design. Suppose that you are interested in the effects of a particular study strategy on memory for verbal information. You decide to use two different study strategies: Repetition and Imagery. Your participants are shown a list of 30 words, one at a time. One half of your participants is told to repeat each word over and over as it appears. The other half of your participants is told to create an image of each word as it appears. [The independent variable, or factor, would then be the study strategy.] After presenting the list, you provide a distractor task (e.g., count backward from 571 by threes), then ask the participants to write down as many of the words as they can remember. [The dependent variable would then be the number of words recalled.] For this factor, your null hypothesis would be: H0: Repetition = Imagery Compute a one-way ANOVA on these data: Repetition Imagery Sum (T) SS Males 14 13 10 11 17 19 24 25 20 22 175 258.47 Females 13 15 12 14 16 19 23 24 25 24 185 234.46 Sum (T) 135 225 360 (G) X2 = 6978 SS 42.5 50.5 Source SS df MS F Strategy Within (Error) Total Now, suppose that you included an number of men and women in the experiment. In fact, the first 5 participants in each group were males and the second 5 participants were females. You could now reanalyze the data as a one-way ANOVA to look at the impact of gender. Thus, you would ignore the effects of strategy and analyze only for the impact of
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