Module - ANOVA/ANCOVA
1. ANOVA-What is the reasoning for conducting post-hoc analyses?
2. ANOVA-When would you choose for your post hoc analyses the method by: Fisher's least significant difference (LSD), Sheffé's, or Bonferroni?
ANCOVA-the interpretation of ANCOVA outputs is not simple. What are we looking for in them to explain the effects of the IVs and Covariates on the DV?
Learning Outcomes
Upon successful completion of this module, the student will be able to satisfy the following outcomes:
• Case
o Choose an ANOVA test when appropriate per the study hypotheses and variables' level of measurement.
o Review, conduct, and interpret statistical ANOVA tests.
o Review, conduct, and interpret statistical ANOVA post-hoc tests.
• SLP
o Implement within a "real-world" project: The definition of research questions and their derivative hypotheses; Examine data; perform appropriate statistical test: t test, ANOVA/ANCOVA, Chi Square; interpret and report results.
• Discussion
o Explain: (a) the reasoning for choosing and conducting ANOVA post-hoc analyses, and (b) the interpretation of ANCOVA tests.
Module Overview
1. We will continue to look at Inferential statistical procedures which utilize research data sampled from a study population to make inferences about that particular study population.
2. Inferential statistics generally come from the family of statistical models known as the General Linear Model.
3. The statistical methods used frequently in research are the t-test (Module 3), ANOVA/ ANCOVA (Module 4), and MANOVA/MANCOVA, regression analysis, factor analysis covered in the following course of DEL 618).
4. In this module we will focus on Analysis of Variance (ANOVA) and introduce Analysis of Covariance (ANCOVA).
5. If the t test compared the means of two nominal sample categories (sub-groups) on a continuous dependent variable, then the ANOVA is essentially a series of t tests that are run when we have a nominal variable with three or more categories (sub-groups). For example: the academic scores (DV) of students based on their four Instructors (IV): Adam, Eve, Jack, Jill.
6. The ANOVA F test statistic and its level of significance (p value) allows us to decide whether the difference between the subgroups is statistically significant, and consequently decide on our null hypothesis.
7. Furthermore, an in-depth post-hoc examination of the results will identify which of the sub-groups between themselves is significant (or not).
8. When we have one IV we conduct a One-Way ANOVA, and when we have two IVs we conduct a Two-Way ANOVA.
9. Analysis of covariance (ANCOVA) - When we have in addition to our continuous DV and categorical IV some covariates, we will need to conduct an ANCOVA analysis which tests whether certain factors have an effect on the outcome variable after removing the variance for which quantitative predictors (covariates) account. The inclusion of covariates can increase statistical power because it accounts for some of the variability in the DV.
10. It is recommended that you FIRST view the modular Case and SLP assignments, and see what is required of you to do. With this in mind, review the Background page for reading and support materials.
Attachment:- Assignment Module Background.rar