Review of ANOVAReview of ANOVA

PSY 340Fall 2013

Thursday, October 31

RecentlyRecently

We reviewed interpretations of main effects and interactions in two-factor ANOVA models

We learned how to compute F ratios to test the statistical significance of the main effects and interaction in a two-factor ANOVA

We compared computational and definitional formulas for two-factor ANOVA calculations

We learned how to conduct a two-factor between groups ANOVA in spss, and how to read the spss output from this type of analysis

Questions about any of this?Today we will review 1-way, repeated measures,

and factorial ANOVA in anticipation of Monday’s exam

First, a little more practice First, a little more practice with SPSSwith SPSSStudy: Do young men sublimate unacceptable sexual urges by producing more creative art?20 men with sisters, half told to imagine they went on vacation with their girlfriend, half told to imagine going with their sister. Within each group, half were shown a picture of a swimsuit model and half shown a picture of a more plain looking woman.Then they are told to make some sculpture and write a haiku, and their art is judged by experts. Hypothesis: sublimation better art

The data:The data:

Group I: Swimsuit model / girlfriend2,3,3,5,1

Group II: Swimsuit model / sister7,6,3,8,9

Group III: Plain looking picture / girlfriend2,4,4,2,2

Group IV: Plain looking picture / sister3,3,1,2,3,

What are the IV’s and DV?What are the IV’s and DV?

Group I: Swimsuit model / girlfriend2,3,3,5,1

Group II: Swimsuit model / sister7,6,3,8,9

Group III: Plain looking picture / girlfriend2,4,4,2,2

Group IV: Plain looking picture / sister3,3,1,2,3,

How to set up the data in How to set up the data in SPSS?SPSS?Group I: Swimsuit model / girlfriend2,3,3,5,1

Group II: Swimsuit model / sister7,6,3,8,9

Group III: Plain looking picture / girlfriend2,4,4,2,2

Group IV: Plain looking picture / sister3,3,1,2,3,

Exam III (Monday 11/5) Covers first 14 chapters (emphasis on

chapters 12-14) Closed book (materials will be

provided) Bring calculator Bring pencil Emphasis on material covered in class Difficulty level similar to Exams I & II,

but much more material to know Some SPSS and Excel may be required

Old Material Terms from chapter 1 Ways to describe distributions (using tables, graphs,

numeric summaries of center and spread) Z-scores Probability Characteristics of the normal distribution Use of the unit normal table Central Limit Theorem & distribution of sample means (a

number of students missed this question last time - look for it to appear again!!!)

Standard error of the mean (σM) Hypothesis testing (four steps)

Old Material: t-tests•Effect sizes and power•Type I and Type II error•Similarities/differences among four inferential tests:

•One-sample Z test•One-sample t-test•Independent samples t-test•Paired samples t-test

•When to use which test• Formulae for each statistic

•Numerator (difference between means)•Denominator / standard error•Degrees of freedom

•Use of the t-table with various alpha levels and one-tailed and two-tailed scenarios

Old Material: t-tests

•Assumptions of the t-tests•Levene’s test for equality of variance•Using SPSS/Excel to conduct t-tests•Setting up the data properly•Knowing which commands to use•Interpreting the output

•Estimation and confidence intervals with t formulae

•One-Way ANOVA

• Calculating total, between, and within condition SS, df, and MS

• Calculating and interpreting the F-Ratio, using the F table

• Effect sizes, assumptions, and how to write the results in a research paper

• Experiment-wise error, Post hoc tests and planned comparisons (know what they are, why they are used, and how to conduct and interpret them using SPSS - no by-hand calculations)

New Material: ANOVA

•Repeated Measures ANOVA

• Calculating total, between condition, within condition, between participants, and error SS, df, and MS

• Calculating and interpreting the F-Ratio, using the F table

• Effect sizes, assumptions, and how to write the results in a research paper

• Know why a repeated measures ANOVA is more powerful than a between-groups ANOVA

New Material: ANOVA

•Factorial ANOVA

• Understanding and interpreting main effects and interaction effects in a two-factor scenario

• Calculating total, between condition, Factor A, Factor B, interaction, and within condition SS, df, and MS

• Calculating and interpreting the three F-Ratios, using the F table

• Effect sizes, assumptions, and how to write the results in a research paper

New Material: ANOVA

• ANOVA in SPSS

• Know how to conduct one-way, repeated measures, and factorial ANOVAs using spss.

• Know how to set up the data for each kind of ANOVA

• Know how to inerpret the output for each type of ANOVA

• In general:

• Be able to fill in ANOVA tables for each kind of ANOVA

• Be able to tell which type of test to conduct (Z, one-sample t, related-samples t, one-way ANOVA, repeated measures ANOVA, factorial ANOVA) based on description of a study or details of a data set (study the flow chart!)

New Material: ANOVA