Figure:
A researcher was interested in the effects of arousal and personality on individuals' GRE test performance.The personality variable he examined was individuals' level of introversion-extraversion.Based on questionnaire responses,each participant was classified as an "extravert" or an "introvert." The researcher manipulated arousal level by giving caffeine to participants prior to administering a practice GRE test.Participants were randomly assigned to a high-caffeine condition,a medium-caffeine condition,or the no-caffeine conditions.All participants then completed a practice version of the quantitative portion of the GRE.
Suppose the researcher observed the following means for each group:
-Based on these findings,the researcher can
A)predict individuals' quantitative GRE score if he knows whether they are introverted or extraverted.
B)claim that individuals' level of introversion or extraversion causes different performance on the GRE.
C)neither (A)nor (B)
D)both (A)and (

Question

Figure:
A researcher was interested in the effects of arousal and personality on individuals' GRE test performance.The personality variable he examined was individuals' level of introversion-extraversion.Based on questionnaire responses,each participant was classified as an "extravert" or an "introvert." The researcher manipulated arousal level by giving caffeine to participants prior to administering a practice GRE test.Participants were randomly assigned to a high-caffeine condition,a medium-caffeine condition,or the no-caffeine conditions.All participants then completed a practice version of the quantitative portion of the GRE.
Suppose the researcher observed the following means for each group: 
-Based on these findings,the researcher can
A)predict individuals' quantitative GRE score if he knows whether they are introverted or extraverted.
B)claim that individuals' level of introversion or extraversion causes different performance on the GRE.
C)neither (A)nor (B)
D)both (A)and (

Quizplus · Accepted Answer

While the means do suggest that there is a difference in performance between introverts and extraverts, and between different caffeine conditions, this study cannot establish a causal relationship between introversion-extraversion and GRE performance or the effect of caffeine on GRE performance. The study only measures correlations between these variables, and there may be other factors at play that could explain the observed differences in performance. Additionally, the study did not control for other potential confounding variables, such as participants' baseline caffeine consumption or sleep patterns, that could also affect GRE performance. Therefore, the researcher cannot make any definitive claims about the causal relationships between these variables based on this study alone.

Figure: a Researcher Was Interested in the Effects of Arousal and and Personality