Statistics Chapter on Single-Factor Designs

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Questions and Answers

Which design type employs random assignment to groups?

Matched groups

Independent groups (correct)

Repeated-measures design

Ex post facto

What is the primary statistical test used for analyzing independent groups?

Independent samples t-test (correct)

Dependent samples t-test

Z-test

One-way ANOVA

In which design are participants matched on a specific variable before assigning them to conditions?

Ex post facto design

Matched groups design (correct)

Independent groups design

Single-factor two-level design

Which statistical test helps determine overall significance when more than two levels are involved?

One-way ANOVA Signup and view all the answers

What is the key advantage of using multi-level designs over two-level designs?

They allow for non-linear effects. Signup and view all the answers

Which potential error increases when performing multiple t-tests?

Type I Error Signup and view all the answers

What follows after a significant one-way ANOVA to identify specific group differences?

Post-hoc tests Signup and view all the answers

In a single-factor, multilevel design with 4 levels, how many t-tests would one need to conduct for all possible comparisons?

6 Signup and view all the answers

What is a key ethical advantage of the wait list control group?

It allows participants to receive treatments after the study is completed. Signup and view all the answers

How does a yoked control group function in relation to an experimental group?

Control group members are linked to specific experimental members to match the number of treatments received. Signup and view all the answers

What potential problem does a yoked control group address in the sleep study example?

The timing and frequency of awakenings across all participants. Signup and view all the answers

In a sleep study with REM deprivation, what factor is not accounted for in the experimental group without using a yoked design?

The time of night at which subjects are awakened. Signup and view all the answers

What is the main objective of using a wait list control group?

To ensure treatment effects can be observed without ethical concerns. Signup and view all the answers

What assumption is made when using a yoked control group design in an experiment?

The behaviors of the experimental subjects directly influence the treatment given to the yoke pairs. Signup and view all the answers

What is the main characteristic that distinguishes the yoked control group from other control group designs?

It matches control subjects to specific experimental subjects based on behavior. Signup and view all the answers

What could be a limitation of using a wait list control group in a psychological study?

Participants in the wait list may experience less motivation compared to treatment groups. Signup and view all the answers

What should be done if a one-way ANOVA is found to be not significant?

End the analysis without further tests. Signup and view all the answers

When should a bar graph be used in presenting data?

When the independent variable is discrete. Signup and view all the answers

Which of the following best describes a placebo control group?

A group that receives a treatment without the active ingredient. Signup and view all the answers

What is a key difference between continuous and discrete variables?

Continuous variables can take on any value within a range. Signup and view all the answers

In a study where subjects consume drinks, what is the purpose of using a placebo control group?

To prevent expectations from influencing the results. Signup and view all the answers

Which type of graph would be appropriate for presenting data if the independent variable is continuous?

Line graph Signup and view all the answers

What is the main reason for stopping the analysis after a non-significant one-way ANOVA?

It indicates no differences exist among the groups. Signup and view all the answers

Which of the following statements about presenting data is true?

Bar graphs indicate the mean for each condition with bars that do not touch. Signup and view all the answers

Study Notes

Single-Factor Two-Level Designs

Independent variable (IV) can be manipulated or a subject variable
Independent groups: IV is manipulated, random assignment to groups
Matched groups: Participants matched on a variable before random assignment to groups
Ex post facto: IV is a subject variable (e.g., gender, age)
Repeated-measures design: Each participant is exposed to all levels of the IV (also known as within-subjects design)
A t-test is used to determine if the difference between two groups is significant
Independent samples t-test is used for independent groups and ex post facto designs
Dependent samples t-test is used for matched groups and repeated-measures designs

Single-Factor - Multilevel Designs

More than two levels of the IV are investigated
This allows for the discovery of non-linear effects
Multiple t-tests should not be used for comparing multiple levels due to an increased chance of Type I error
Type I error occurs when you conclude there is a difference between groups when there is not, often due to chance
Formula to calculate the probability of Type I Error: 1-(1-alpha)^c , where c = number of comparisons and alpha = usually 0.05

Analyzing Single-Factor Multilevel Designs

One-Way ANOVA (Analysis of Variance) is used to analyze multilevel designs
ANOVA tests for an overall level of significance
It does not tell you specifically which conditions are different
Post-hoc Tests are used to determine which conditions are significantly different if the ANOVA is statistically significant
Post-hoc tests are not performed if the one-way ANOVA is not significant

Presenting Data

Data can be presented in sentences, tables, or graphs
Line graphs are used when the IV is continuous
Bar graphs are used when the IV is discrete
Continuous variable: has an infinite number of potential values (e.g., alcohol dose, age)
Discrete variable: distinct categories with no intermediate points (e.g., types of exercise, eye color)

Special Types of Control Group Designs

Placebo control group: receives something that appears to be the treatment but does not contain the active ingredient
Used to control for subject expectations about the treatment
Wait list control group: receives the treatment after the study is over
Yoked control group: Each control group member's treatment is linked to the behavior of a specific participant in the experimental group
Yoked control groups are used when procedures vary based on individual behavior
Example: REM deprivation study using yoked control groups to ensure that the number and timing of awakenings are identical for both groups

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Description

Explore the key concepts of single-factor two-level and multilevel designs in statistics. This quiz covers independent variables, t-tests, and the implications of design choices like matched and repeated measures. Test your understanding of how these designs affect statistical analyses.