Which of the following things can be done to reduce measurement error?

Which of the following is the correct factorial notation for the study below?  

What is the difference between a cross-over interaction and a spreading interaction?

Dr. Morimoto is curious as to whether exposing people to violent video games causes them to be more aggressive. He assigns half his participants to play a video game for 5 minutes and the other half to play for 7 minutes. He finds that there is no relationship between playing the game longer and being more aggressive. What might be to blame for this null effect?

Regression results can indicate whether a third variable affects the relationship and address the internal validity. If a third variable is the reason behind why the predictor and the criterion is correlated (e.g., video gaming experience is the reason why male’s spatial ability is better than females), then the correlation between the predictor and criterion becomes _____ when the third variable is controlled for.

When examining an association in which one variable is categorical and one is quantitative, which of the following is most likely to be used?

By reading literature, I estimate that the correlation between my variables of interest is 0.2. To reach statistical significance in my study, I need at least ____ participants.

RESEARCH STUDY 9.1: Dr. Farah is an educational psychologist who is interested in studying the potential causal relationship between doing homework and academic achievement. In January, Dr. Farah has her students report their fall GPA (a measure of academic achievement) and estimate how many hours they spent doing homework during a typical week in the fall semester. In May, Dr. Farah measures the same variables again (the estimated number of hours spent doing homework during a typical week in the spring semester and their spring GPA). She finds the following correlations:   Variable A Variable B Correlation Coefficient Correlation 1 Fall number of hours of homework Fall semester GPA .83* Correlation 2 Fall number of hours of homework Spring number of hours of homework .36* Correlation 3 Fall number of hours of homework Spring semester GPA .69* Correlation 4 Fall semester GPA Spring number of hours of homework .18 Correlation 5 Fall semester GPA Spring semester GPA .45* Correlation 6 Spring number of hours of homework Spring semester GPA .80* *Indicates a statistically significant relationship.   What type of study design is Dr. Farah using?

How to determine if the third variable Z, is a moderating variable between X and Y statistically?

In the study below investigating the correlation between age and spatial ability, why did participants’ spatial ability start to increase from age 75? What kind of validity is threatened in this age range?