How is R-squared calculated, and what information does this give you?© BrainMass Inc. brainmass.com October 24, 2018, 7:49 pm ad1c9bdddf
R square, that is the coefficient of determination = the amount of the variation in y that is explained by the regression line.
It is Explained variation/Total variation ...
This explains the Computation of R-squared
T Test on Mean Difference and Computing R Squared
Masculine themed words are frequently used in job recruitment materials, especially for job advertisements in male-dominated areas. the same study found that these words also make the jobs less appealing to women. in a similar study, female participants were asked to read a series of job advertisements and then rate how interesting or appealing the job appeared to be. Half of the advertisements were contracted to include several masculine-themed words and the others were worded neutrally. the average rating for each type of advertisement was obtained for each participant. for n=25 participants, the mean difference between the two styles of advertisements is MD=1.32 points (neutral ads rated higher) with SS=150 for the difference scores.
t distribution, degrees of freedom= 21
Is the result sufficient to conclude that there is a significant difference in the ratings for two types of advertisements?
t = ________
Compute r2 to measure the size of the treatment effect (round to three decimal places.)
write a sentence describing the outcome of the hypothesis test and the measure of effect size as it would appear in a research report.
Female participants (did not rate, rated) job recruitment materials with masculine-themed words significantly different than job recruitment materials with neutral words, (( t25)=1.205, t(25)=2.699, t(24)=2.588, t(24)=2.640) , (p<.05, t(25)=2.604, s=2.5, up=1.32) , (r=0.467, r2=0.095, r=0.315, r2=0.225).
suppose a researcher obtains a sample of n=16 adults who are between the ages of 65 and 75. the researcher uses a standardized test to measure cognitive performance for each individual. the participants then begin a 2 month program in which they receive daily doses of the blueberry supplement. at the end of the 2 month period the researcher again measures cognitive performance for each participant.
the results show an average increase in performance of MD= 7.4 with SS=1,215. does this result support the conclusion that the antioxidant supplement has a significant effect on cognitive performance? use a two tailed test with o=.05.
t distribution degrees of freedom=21
t-crtitical= ± _____
the results indicate
*rejection of the null hypothesis, the antioxidant does not have a significant effect on cognitive performance
*failure to reject the null hypothesis, the antioxidant does not have a significant effect on cognitive performance
* failure to reject the null hypothesis, the antioxidant does have a significant effect on cognitive performance
*rejection of the null hypothesis, the antioxidant does have a significant effect on cognitive performance
construct a 5% confidence interval to estimate the average cognitive performant improvement for the population of older adults.