In a study conducted by the department of mechanical...

In a study conducted by the Department of Mechanical Engineering and analyzed by the Statistics Consulting Center at the Virginia Polytechnic Institute and State University, the steel rods supplied by two different companies were compared. Ten sample springs were made out of the steel rods supplied by each company, and the "bounciness" was studied. The data are as follows: Company A: 9.3 8.8 6.8 Company B: 11.0 9.8 9.9 10.2 8.7 8.5 6.7 8.0 6.5 9.2 7.0 10.1 9.7 11.0 11.1 10.2 9.6 Can you conclude that there is virtually no difference in means between the steel rods supplied by the two companies? Use a P-value to reach your conclusion. Should variances be pooled here?

Transcript

00:01 John, you have that there are a study conducted by the department of mechanical engineering and analyzed by the statistics consulting center at a virginia polytech institute and state university.

00:13 You have that there are two different companies were being compared.

00:18 And you have that there are 10 were made of steel supplied by each company and looking at their bounciness.

00:27 And for company a, you are supplying me only with a sample size of three.

00:36 And for company b, you're giving me a sample size of 17.

00:42 So i don't know how these two are segregated.

00:47 And then it says, should the variances be pooled? well, for pooling the variances, i would say no.

00:58 Because you don't have information that you know that they're the same, especially when you have these differing sample sizes.

01:05 Now, again, i could go through and put the first three and then the other 17 put in class b or in company b, or i could take the first seven that are listed down in a and then assume that the last ones are in there.

01:24 That's what i'm going to do.

01:25 I'm going to use the 9 .3, the 8 .8, the 6 .8, and then i'm going to put the 11, the 9 .8, the 9 .9, the 10 .2, and put the first 10 in company a.

01:42 I don't know if that's right.

01:43 Hopefully it is.

01:45 Let me quickly put the data in.

01:46 Okay, so i put 10 values in the for a and i put 10 in for b.

01:57 And again, i used the first ones, the first 10, the first 10, so these values up to 6 .7, i put in company a.

02:09 And then i put the remaining in b.

02:11 So let me give you the information for that...