### Research Methods in Experimental Psychology ## How to Select the Correct Statistical Test

### THINGS TO CONSIDER

• How many variables do you have?
• How many Independent Variables (IV)
• How many Dependent Variables (DV)
• What types of data do you have?
• Is the IV(s) Continuous or Categorical
• Is the DV(s) Continuous or Categorical

### STEPS

• Step One: Based on the number of variables you have, select the Univariate (1 variable), Bivariate (2 variables), or Multivariate (≥3 variables) section below to find your test.
• Step Two: Determine the types of measures (i.e., continuous or categorical) your independent variable(s) and dependent variable(s) are to find the correct tests for your data using the grids within the univariate, bivariate, and multivariate sections below.
• Step Three: Once you've found the correct test, scroll down to find the instructional videos for your test in the video sections below.

### MEASUREMENTS REVIEW

#### INDEPENDENT VS DEPENDENT VARIABLES

• Independent Variable (IV): In an experiment, it is the variable that is intentionally changed (manipulated) or introduced in order to observe its effect on the Dependent Variable
• Independent Variables also include Person Variables, such as gender, race, ethnicity, personaly traits, etc.
• Dependent Variable (DV): In an experiment, it is the effect or event observed and expected to change as a result of the independent variable being applied or changed.

#### CONTINUOUS VS CATEGORICAL MEASUREMENTS

##### CONTINUOUS MEASURES

Sometimes called quantitative variables. Called Scale data in SPSS.

Interval variables that can be measured along a continuum and they have a numerical

• Intelligence
• Aptitude
• Temperature

Ratio variables are interval variables, but with the added condition that 0 (zero) of the measurement indicates that there is none of that variable.

• Reaction time
• Weight
• Age
• Frequencies of Behavior

##### CATEGORICAL MEASURES

Sometimes called qualitative, discrete, or dichotomous variables. Called Ordinal and Nominal data in SPSS.

Ordinal data that has a distinct order. There’s a meaning to the order.

• Two, Three, And Four Star Restaurants
• Ranking TV Programs By Popularity
• 1st, 2nd, 3rd Place Winners!

Nominal data are distinct groups with no meaning to the order.

• Gender
• States
• Colors

### UNIVARIATE ANALYSIS GRID (One Variable)

VARIABLE TYPE TEST
Categorical Frequencies
Categorical Explore for Categorical Data
Continuous Descriptives
Continuous Explore for Continuous Data

### BIVARIATE ANALYSIS GRID (Two Variables)

#### TEST

Continuous Continuous Correlation
Categorical (≥ 2 groups) Categorical (≥ 2 groups) Chi-Square
Categorical (2 groups) Continuous Independent Samples T-test
Categorical (1 group 2 conditions) Continuous Paired Samples T-test
Categorical (≥ 2 groups) Continuous One-Way Between Subjects ANOVA
1 Group Continuous (≥ 3 conditions) One-Way Within Subjects ANOVA (Repeated Measures)

### MULTIVARIATE ANALYSIS GRID (Three or More Variables)

#### TEST

Continuous Continuous Continuous Simple Linear Regression
Continuous (≥ 2) Continuous Multiple Regression
Continuous (≥ 3) Path Analysis/Structural Equation Modeling (SEM; Predictive Modeling)
Continuous Continuous or Categorical Continuous Stepwise Multiple Regression
Continuous Continuous or Categorical Continuous Hierarchical Regression
Continuous (≥ 1) Categorical (≥ 1) Categorical (2 groups) Logistic Regression
Continuous (≥ 1) Categorical (≥ 1) Categorical (≥ 3 groups) Multinomial Logistic Regression
Categorical Categorical Categorical Log-Linear Regression
Categorical Categorical Continuous Factorial ANOVA (2 X 2 ANOVA)
Categorical Categorical Continuous One-Between-One-Within ANOVA (a.k.a. Mixed Factorial)
Categorical Categorical or Continuous Continuous ANCOVA
Categorical (≥ 1) Categorical (optional) Continuous (≥ 2) MANOVA
Categorical (≥ 1) Categorical (optional) Continuous (≥ 2) MANCOVA

### MULTIVARIATE ANALYSIS (VIDEOS)

#### MANCOVA 