Chapter 13 Pre-lect Quiz Flashcards
A researcher examines the effectiveness of different body lotions by having 12 participants apply four different lotions to the same, unique body locations daily for two weeks. For example, lotion #1 is always applied to the right thigh, while lotion #2 is applied to the upper right arm. The participants were randomly selected at a drugstore in a busy area. What is the null hypothesis for this study?
The effectiveness of the four different lotions is the same, on average.
A researcher conducts a within-groups ANOVA, fails to find a significant F statistic for the independent variable, and finds an R2 value of 0.02. What does the effect size statistic tell us about the research?
The conventions for R2 indicate that this is a small effect, which would help to explain the non-significant F statistic.
When it is not possible to have participants experience all levels of the independent variable, an alternative approach to a within-groups design can be used. This approach offers the same advantage in statistical power as the within-groups design by:
using participants in each group that are matched on variables of interest that we want to control across conditions.
Which of the following is a potential problem with a matched-groups design for ANOVA?
We may not be aware of all of the important variables that need to be matched across groups.
When using a one-way within-groups ANOVA, the variability due to individual differences is reduced resulting in:
a larger F statistic making it easier to reject the null hypothesis.
A researcher examines the effectiveness of different body lotions by having 12 participants apply four different lotions to the same, unique body locations daily for two weeks. For example, lotion #1 is always applied to the right thigh, while lotion #2 is applied to the right upper arm. The participants were randomly selected at a drugstore in a busy area. Which assumptions for the ANOVA are met?
random selection
A researcher interested in the impact of “dress-down Fridays” on work performance decides to study the impact of attire at work. She randomly selects 35 people at a large company to participate. Across the course of three weeks, she has all 35 participants experience working under three different levels of work attire: casual, dress-casual, and formal attire. What statistical analysis would be appropriate for her design?
one-way within-groups ANOVA
The National Collegiate Athletic Association (NCAA) cares about success for athletes both in their sports and in their education. Imagine a researcher hired by the NCAA wants to know how athletes’ academic performance is affected by the stage of their competitive season. She examines performance in the pre-season, throughout the active competitive season, and post-season, having 150 athletes, from across several different sports, assessed during each period. What statistical analysis would be appropriate for this research?
one-way within-groups ANOVA
Within-groups variability is reduced in the one-way within-groups ANOVA because:
by using the same participants across all levels of the independent variable, we have removed differences between groups due to individual variability.
