A Study Was Conducted to Look at Whether Caffeine Improves

question 10

Multiple Choice

A study was conducted to look at whether caffeine improves productivity at work in different conditions.There were two independent variables.The first independent variable was email,which had two levels: 'email access' and 'no email access'.The second independent variable was caffeine,which also had two levels: 'caffeinated drink' and 'decaffeinated drink'.Different participants took part in each condition.Productivity was recorded at the end of the day on a scale of 0 (I may as well have stayed in bed) to 20 (wow! I got enough work done today to last all year) .Looking at the group means in the table below,which of the following statements best describes the data?

• A)There is likely to be a significant main effect of caffeine.
• B)A significant interaction effect is likely to be present between caffeine consumption and email access.
• C)The effect of email is relatively unaffected by whether the drink was caffeinated.
• D)The effect of caffeine is about the same regardless of whether the person had email access.

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Definitions:

Stepwise Regression

A statistical method of building a model by adding or removing predictors based on their statistical significance.

Independent Variable

A variable in an experiment that is manipulated or changed by the researcher to observe its effects on the dependent variable.

Simple Regression

An analytical approach that employs a linear equation to depict how a dependent variable is influenced by one independent variable.

Stepwise Regression

A method of regression analysis in which the selection of predictive variables is carried out by an automatic procedure, adding or removing predictors based on specific criteria.