Research Methods in Experimental Psychology

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STATISTICS

SELECTING THE CORRECT STATISTICAL TEST

(Tutorial Videos Below)


THINGS TO CONSIDER

STEPS

  • 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
  1. 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.
  2. 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, or multivariate section below.
  3. Once you've found the correct statistical test, click the button to view the instructional video for performing your test in SPSS or EXCEL.

MEASUREMENT REVIEW

INDEPENDENT VARIABLES

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 MEASURES

CATEGORICAL MEASURES

Sometimes called quantitative variables. Called Scale data in SPSS.


Interval scales hold no true zero and may represent values below zero. Zero-point in an interval scale is arbitrary. For example, the temperature can be below 0 degrees Celsius and into negative temperatures.

  • 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. The ratio scale has an absolute zero or character of origin. Height and weight cannot be zero or below zero.

  • Income
  • Weight
  • Age

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

TUTORIAL VIDEOS

Description Tutorial Video
Basic Introduction to the SPSS Interface
Creating and Coding Variables in SPSS
Importing, Exporting & Saving other file-types in SPSS: Excel, CSV, Text
Select IF Cases allows you to select subsets of cases. Unselected cases are not included in the analysis but remain in the dataset. You can use the unselected cases later in the session if you turn off filtering.
Split File splits the data file into separate groups for analysis based on the values of one or more grouping variables. If you select multiple grouping variables, cases are grouped by each variable within categories of the preceding variable on the Groups Based On list. For example, if you select gender as the first grouping variable and minority as the second grouping variable, cases will be grouped by minority classification within each gender category.
The Recode into Different Variables function allows you to reassign the values of existing variables into new values for a new variable.
Computing variables in SPSS refers to computing with existing variables to create new variables.For example, you may want to add all of the ratings of several questions having to do with shyness to calculate a total shyness score.
APA Formatting Tips for Tables with SPSS
VARIABLE TYPE SPSS EXCEL
Categorical
Categorical
Continuous
Continuous

IV

DV

SPSS

EXCEL

Continuous Continuous
Categorical (≥ 2 groups) Categorical (≥ 2 groups)
Categorical (2 groups) Continuous
Categorical (1 group with 2 conditions) Continuous
Categorical (≥ 3 groups) Continuous
Categorical (1 group with ≥ 3 conditions) Continuous (≥ 3 conditions)

IV 1

IV 2

DV

SPSS

EXCEL

Continuous Continuous Continuous
Continuous (≥ 2) Continuous
Continuous (≥ 3)
Continuous Continuous or Categorical Continuous
Continuous Continuous or Categorical Continuous
Continuous (≥ 1) Categorical (≥ 1) Categorical (2 groups)
Continuous (≥ 1) Categorical (≥ 1) Categorical (≥ 3 groups)
Categorical Categorical Categorical
Categorical Categorical Continuous
Categorical Categorical Continuous
Categorical Categorical or Continuous Continuous
Categorical (≥ 1) Categorical (optional) Continuous (≥ 2)
Categorical (≥ 1) Categorical (optional) Continuous (≥ 2)
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