22 Apr 2020

Posted on:

06 Apr 2020

1

# R T Test Weightloss example E11.8

Hi there, I don't understand the Solution for E11.8.

H0: muB-muA >=0      ok! alternativ should be then
H1: muB-muA <0 The solution's t.test Syntax is:
dep.t.test <- t.test(weight\$before, weight\$after, paired = TRUE, alternative = "g")   shouldn't it be: dep.t.test <- t.test(weight\$before, weight\$after, paired = TRUE, alternative = "less")   Thanks for the Help.
Greets
Alex
1 answers ( 0 marked as helpful)
Instructor
Posted on:

22 Apr 2020

0
Hi Alex, thanks for the question and apologies for the delay in response -- unfortunately, this got lost in the threads somehow. Not quite. But I do see now that the way I've stated the H0 might be a little confusing -- I am editing the file now. Anyhow, so... The code in the solution is going off of this formulation of the hypotheses: H0: muB - muA <= 0 OR D0 <= 0 (as defined here, the D is a negative number; or in the After condition people are either keeping their weight or increasing it) H1: muB - muA > 0 OR D1 > 0 (as defined here, the D is a positive number) So, in our code, we'd set the alternative argument in the code to "g" or the true difference in means is "more than zero"! `dep.t.test <- t.test(magn\$Before, magn\$After, paired=TRUE, alternative = "g")` Hopefully, this is helpful.  Thank you for the question!  Best wishes,  Simona
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