The overall goal of this learning activity is to train learners on how to conduct a basic one-way ANOVA. This is a commonly used test in social sciences when researchers compare more than two groups.

Load the data file Ex8Q1.sav. Download Load the data file Ex8Q1.sav.This file contains the data collected during a study of the effects of time on memory for details of a crime. A total of thirty-five participants watched a video of a crime. They were then interviewed either one, two, or three days later. Participants’ memory for the crime details was scored out of 50.

Write an APA paper reporting your findings; Include the below components:

Introduction: What is ANOVA? What is the test used for? What are the statistical assumptions for ANOVA? (6 points)
Run a one-way ANOVA to test the hypothesis that the duration of the delay between encoding and recall will affect recall accuracy. Use one-way ANOVA. (2 points)

First report the results of the Leveneâs test. What do the results tell us? Explain if the results of the ANOVA are significant or not. Report the effect size (eta squared). For example (F(3,36) = 15.314, p < .001, η² =.56).  Produce an error bar graph for recall accuracy by the delay of recall groups using the chart builder.

Conclusion: Use your findings to answer the question: does each increase in delay result in a significant decrease in the recall?

Resources: Lecture Notes- ANOVA What is ANOVA? Basically, ANOVA uses an F statistic to test if three or more population means are all equal. For example, we could use ANOVA to test if students taking IP820 Statistics taught by the same Instructors in three sections have equal mean scores on a final exam. The null hypothesis for (any) ANOVA is that all population means are exactly equal.

To see if the three groups’ mean scores are different, we want to know how far do the numbers for each sample lie apart? A number that tells us just that is the variance. So, we’ll compute the variance among our 3-sample means.

Here is the data for the example used in the video. Download Here is the data for the example used in the video.

Video: Conducting One-way ANOVA. Refer to page 214 – 239 of Harrison, Kemp, Brace & Snelgar.

Copy of the Results
One-way ANOVA SPSS Results Download One-way ANOVA SPSS Results

Interpreting the Results
Based on the ANOVA table, grouped differently based on recall accuracy? In other words, was the F statistic significant, i.e., was Sig. less than .05? If Sig. is less than .05, the test is significant, meaning that the age distributions are significantly different.

The results should be written following the example in Brace et al. i.e., this is a non-significant finding (F(3,36) =15,314, p =.001, partial È Â² = .56.

Producing an Error Bar
Produce an accurate error bar graph for accuracy of recall by the delay of recall groups using the chart builder.

How to Conduct Post Hoc Tests
Run the ANOVA again, this time selecting for Bonferroni Post Hoc Test (see planned and unplanned comparisons.

Interpreting Post Hoc Comparisons
Pay attention to the Sig. if it is less than .05, then there is a significant difference between the compared groups. So, take a look at the mean scores in the descriptive table, i.e., the mean (M =66.70) for unmasked, for grey blob (M =55.70), for pixilated (M = 57.70), and negated (67.20).

In the post hoc table, we can compare the mean difference between the groups. The mean difference simply means the difference between the means, i.e., the mean difference between unmasked and grey blob is 11.00.

Hint: if there is an asterisk next to the mean difference, it implies that the difference is statistically significant.