Group 1 of dogs went on a 20 min walk and Group 2 of dogs...

Group 1 of dogs went on a 20 min walk and Group 2 of dogs went on a 30 min walk. You conduct a t-test to compare how long they sleep after their walks (Group 1: M = 2.3 hours, SD = 0.5 hours; Group 2: M = 2.9 hours, SD = 0.65 hours). You find a p value of .03. Which of the following is TRUE? ? the difference between the two groups is meaningful ? there is not a statistically significant difference between the two groups ? dogs who walked 30 min slept less than dogs who walked 20 min ? there is a statistically significant difference between the two groups

Transcript

0:00 So you have two samples.

00:02 We have, first of all, this is for the country, dog walkers, and you had 21 people, and the mean number of hours was 15 with a standard deviation of four.

00:14 And then we had the city dog walkers.

00:17 And that sample size was 23, with the mean being 10 hours, and a standard deviation of 3.

00:24 And you said a 0 .5 alpha level, i think you mean a 0 .05.

00:30 So we'll use a 5 % significance level.

00:33 And so we will be assuming that the mean for the country is equal to the mean for the city.

00:42 Alternately, that the mean for the country is bigger than the mean of the city.

00:49 And so we're saying that we believe that that difference in time of country minus city is equal to zero.

00:59 And we're actually getting a difference so we can see five hours, five hours.

01:05 And that area will be our p value.

01:07 So what's the likelihood of sampling and getting that difference between them being five? and that's going to be having our test statistic, which will be a t value.

01:18 And we're going to use the conservative of 20 degrees of freedom, which will be the lesser of that.

01:24 We're going to convert this into a test statistic.

01:27 So we're going to take the five minus what we're assuming, divided by, and then we're going to have that the standard deviation squared divided by the sample side, which was either 21 or 23, 21, plus the standard deviation squared divided by the sample size, which i think was 23.

01:49 Yep, 23.

01:51 And so let me just double check that i've put this into my calculator correctly.

01:58 And i don't want to make sure that i don't write something down that i have typed it in improperly...

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