Last answered:

25 Dec 2023

Posted on:

10 Aug 2023


one tailed test or two test?

The question is "Some guy on the internet designed a weight-loss program. You are wondering if it is working. You are given a sample of some people who did the program"

according to the solution given, this is a one tailed test. but my question is this: why isn't it a two tailed test

we can have a null hypothesis as 

H0 : The weight loss program IS working
h1: the weight loss program IS NOT working

wont that be correct? and if so, then this makes it a two tailed test

2 answers ( 0 marked as helpful)
Posted on:

12 Aug 2023


Hi Moffat,

Considering that we're interested only in the weight loss outcome and not in the weight gain outcome, I'd say this is a one-tailed test. The weight loss program decreases people's weight or it doesn't.



Posted on:

25 Dec 2023


Mr Ned, I hope that you answer my question. 

shouldn't the null hypothesis be less than zero ( <0) as we are seeking the difference between before and after which indicates a negative figure? 

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