hth 320 test 2

Which of the following is the strongest correlation?

-.73

A researcher selects two unrelated samples with a mean difference of 1.3. If the standard deviations of each samples are 3 and 2, what is the 'effect' size using the Cohen's d?

0.51

A researcher measures the following correlation between the number of occupational therapy (OT) sessions per month and mood of nursing home residents: r=0.38.

14.4% of the variance in the mood of nursing home residents is explained by the variance in the number of OT sessions

When conducting a one-way between-subjects ANOVA, what are the degrees of freedom in the numerator of the F statistic for a study with n=10 in each of four groups?

3

The correlation between calories eaten at breakfast and weight in pounds is r=-0.86, p<0.01. What can you conclude?

Breakfast calories intake and weight are negatively and strongly associated

Which correlation coefficient would you estimate when you analyze the relationship between the ranking of physicians' quality of care and their monthly income?

Spearman correlation coefficient

A study conducted an independent t test and found: t(198)= 0.987, p>.05 (d=0.13). Which of the following statement is correct?

The Cohen's d is irrelevant because this study did not find a statistically significant difference between the two means.

When conducting a t test, measures of 'effect' size allow researchers to describe:

The proportion of the variance in the outcomes attributable to a treatment

When designing a study, how do you ensure that you have a large probability of making the correct decision if you reject the null hypothesis?

You choose a sample size of 200 and a 5% significance level

A researcher randomly assigned 33 adults to observe a short video depicting a person preparing a low, moderate, or high fat meal. Participants rated how likely they would be to consume the meal. If the between sum of squares equal 30 and the within sum of squares equal 104, what is the decision at a significance level of 5%?

You reject the null hypothesis

A correlation of - 0.34 between physical activity and weight means that higher level of physical activity is strongly related to lower weight.

false

If heat and ice cream consumption are positively correlated, it means that hotter weather causes an increase in ice cream consumption.

false

In Messerli (2012), there is empirical evidence that individuals who consume more chocolate have higher level of cognition.

false

The Cohen's d is a measure of the size of a treatment 'effect', measured as a proportion of the variable's variance.

false

The F statistic obtained from running a one-way analysis of variance will tell you which groups have significantly higher or significantly lower scores as compared with every other group.

false

The Pearson's correlation coefficient of a population is represented by r.

false

The critical value at the significance level of 1% for a F test resulting in F(4,60)=3.51 is 2.52.

false

When comparing the means before and after an intervention and holding other things constant, the Cohen's d statistic is larger if the standard error of the difference is larger as well.

false

When testing the statistical significance of the Pearson's correlation coefficient, the null hypothesis is: H0: p does not equal 0

false

Whether your reject or not the null hypothesis, you always calculate the effect size when you conduct a dependent samples t test.

false

You computes r=0.45 using a sample of 18 individuals. What is your decision if you have a directional research hypothesis and a significance level of 5%

reject null hypothesis

The Pearson's correlation coefficient measures ________________ between two variables.

the strength of the association

All F-tests are nondirectional.

true

Holding other things constant, the power of a study is smaller when you want to minimize you risk of type I error.

true

If you get F(4,60) = 3.51, you conclude that the five groups do not have statistically different means at a significance level of 1%.

true

It is possible to have r=0.25 and find that this correlation is not statistically different from zero.

true

The Pearson correlation coefficient is valid to assess the strength of the relationship between two continuous variables that have a linear relationship.

true

The coefficient of determination can vary between 0 and 1.

true

The mean square between groups is the variance between groups.

true

To conclude that a correlation coefficient is statistically significant, you must have rejected the null hypothesis that this coefficient is zero.

true

When conducting a one sample t test, you use the standard error of the mean to calculate the t statistic and the standard deviation of the mean to calculate the Cohen's d effect size.

true

When testing the statistical significance of the Pearson's correlation coefficient, you can only do a one-tailed test.

true

A statistical procedure used to test whether quality of life and self-reported health each have the same measn among participants in five different groups is called the:

two-way between subjects anova