Question

Directions: For this extra credit assignment, state whether you need to compute an effect size measure for each problem and state how you determined this. If you decide that an effect size is needed, compute and interpret an effect size measure.   

1. A study examined the drinking behaviors of underaged college male and female freshmen. Each participant was asked how many alcoholic beverages he/she consumed in the past seven days. The researchers wanted to determine if there was a difference in the drinking habits of males and females in this age group and found the following:

Females:

Males:

tobt(40) = -1.03

2. On a standard test of attention span in children, a researcher determined that there was a difference in the population between children who have played board games frequently and those who have not. She wanted to know whether the result would be the same when she examined children who played video games extensively. She selected a sample of children who regularly played video games and those who do not and measured their attention spans (larger numbers mean better attention spans). She obtained the following:

Played video games:

Do not play video games:

tobt(27) = 2.77

Answer 1

Answer:

Given that,

For this extra credit assignment, state whether you need to compute an effect size measure for each problem and state how you determined this.

If you decide that an effect size is needed, compute and interpret an effect size measure.

A study examined the drinking behaviors of underaged college male and female freshmen.

Each participant was asked how many alcoholic beverages he/she consumed in the past seven days.

The researchers wanted to determine if there was a difference in the drinking habits of males and females in this age group and found the following:

tobt(40)=-1.03

1. Effect size:

The effect size r2 for when the t-statistic and the number of degrees of freedom df are known, is computed using the follwing formula:

In this case, the information provided is:

t=-1.03

df=40

Pluggin these values into the first formula, we get that:

That means,2.6% of variation in the dependent variable that is expalined by the independent variable.

2. Effect size:

On a standard test of attention span in children, a researcher determined that there was a difference in the population between children who have played board games frequently and those who have not.

She wanted to know whether the result would be the same when she examined children who played video games extensively.

She selected a sample of children who regularly played video games and those who do not and measured their attention spans (larger numbers mean better attention spans).

She obtained the following:

tobt(27)=2.77

The effect size r2 for when the t-statistic and the number of degree of freedom df are known, is computed using the following formula:

In this case, the information provided is:

t=2.77

df=27

Pluggin these values into the first formula, we get that:

That means 22.1% of variation in the dependent variable that is explained by the independent variable.