data analysis

Directions: You will run the four (4) ANOVA data sets using SPSS. There will be three SPSS tests you will run for each data set: [These directions are also available in your textbook on pages 254-256]

1. Upload the data set – click on ANALYZE – click on COMPARE MEANS – Slide over and down and click on ONE-WAY ANOVA. You will see a dialog box with DEPENDENT LIST and FACTOR. [You will find a display of each of the data sets with groups and dependent variables on pages 430-433] Highlight your dependent variable and click the arrow or drag the variable into the Dependent List. Highlight your Group and click the arrow or drag the group into the Factor box.

2. While you are in the dialog box – click on POS HOC – On the next screen click on BONFERRONI – click on okay. (See page 257-258 – blue box for details). You will also see the results of the Bonferroni on page 258.

The reason for the post hoc analysis is to identify where differences actually exist between the three groups. Although the ANOVA will indicate that there are statistically significant differences, it cannot indicate where these differences exist. By running a post hoc analysis, you can see clearly where the significance differences truly lie between the three groups. [Note Figure 13.6 on page 258 for an example]

SPSS will present the ANOVA results. You will see the F-ratio and level of significance. You will also see the variances (Sum of Squares), and Mean Sum of Squares between the groups and within the groups. To better understand the purpose of these calculations, I strongly encourage you to read Chapter 13. Below the ANOVA results will be the Post Hoc results, which clearly indicate where the significant differences are.

3. Because ANOVA does not present descriptive statistics associated with the three groups, you must go back up to ANALYZE (leave the results of the ANOVA and the BONFERRONI on the screen). Click on ANALYZE, scroll down to COMPARE MEANS – slide over and click on MEANS. In the dialog box move your dependent variable (language scores, time, stress, etc.) into the DEPENDENT LIST and your group into the INDEPENDENT LIST – click okay. You will be presented with the sample sizes (n) as well as the means and standard deviations of the three group With these three results, you are now ready to answer the 6 questions listed.

This exercise involves the running of Analysis of Variance (ANOVA) data sets and responding to the six questions related to each data set.  This exercise requires you to run three different SPSS analyses for each data set:

1. The ANOVA data set,

2. A Post Hoc analysis of the results of each data set

3. A running of the Descriptive Statistics for each Data Set.

4. Answering the six questions related to the above.

Data set 1)

1. List the independent variable (example – Preschool Participation), list the groups/levels: Example: Group 1 – 5 hours, Group 2 – 10 hours, Group 3, 20 hours

2. List the dependent variable – example - Language score

3. Provide the means and standard deviations of the three groups

4. Indicate the F-ratio from the ANOVA

5. Indicate the level of statistical significance

6. From the Post Hoc analysis, indicate where the statistical significance actually lies.

(Example – between 5 hours and 20 hours was statistically significant p<.001) There were no statistically significant differences between 5 hour and 10 or 10 and 20 hour.

Data set 2)

1. List the independent variable (example – Preschool Participation), list the groups/levels: Example: Group 1 – 5 hours, Group 2 – 10 hours, Group 3, 20 hours

2. List the dependent variable – example - Language score

3. Provide the means and standard deviations of the three groups

4. Indicate the F-ratio from the ANOVA

5. Indicate the level of statistical significance

6. From the Post Hoc analysis, indicate where the statistical significance actually lies.

(Example – between 5 hours and 20 hours was statistically significant p<.001) There were no statistically significant differences between 5 hour and 10 or 10 and 20 hour.

Data set 3)

1. List the independent variable (example – Preschool Participation), list the groups/levels: Example: Group 1 – 5 hours, Group 2 – 10 hours, Group 3, 20 hours

2. List the dependent variable – example - Language score

3. Provide the means and standard deviations of the three groups

4. Indicate the F-ratio from the ANOVA

5. Indicate the level of statistical significance

6. From the Post Hoc analysis, indicate where the statistical significance actually lies.

(Example – between 5 hours and 20 hours was statistically significant p<.001) There were no statistically significant differences between 5 hour and 10 or 10 and 20 hour.

Data set 4)

1. List the independent variable (example – Preschool Participation), list the groups/levels: Example: Group 1 – 5 hours, Group 2 – 10 hours, Group 3, 20 hours

2. List the dependent variable – example - Language score

3. Provide the means and standard deviations of the three groups

4. Indicate the F-ratio from the ANOVA

5. Indicate the level of statistical significance

6. From the Post Hoc analysis, indicate where the statistical significance actually lies.

(Example – between 5 hours and 20 hours was statistically significant p<.001) There were no statistically significant differences between 5 hour and 10 or 10 and 20 hour.