Questions regarding hypothesis testing
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 This topic has 5 replies, 4 voices, and was last updated 13 years, 8 months ago by Engine Lady.

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April 2, 2008 at 8:38 am #49756
lonelysinParticipant@lonelysin Include @lonelysin in your post and this person will
be notified via email.Hi guys,I have a question regarding hypothesis testing but I believe it it incomplete. Below is the question.”A pilot study indicates that the standard deviation of a particular random variable X is 1.25. How large a sample is required to testH(0) : u = 20
H(1) : u > 20 20 20at the alpha=0.05 and beta=0.05 level if it is important to be able to distinguish between u=20 and u=21??
Does anyone know how to solve the above problem? Any examples?
Rgds,
Lonelysin0April 2, 2008 at 9:56 am #170466From the information given,
Significance level,
a = 0.05
Power = 1b
= 1 – 0.05 = 0.95
Difference in means, d =2120= 1
Standard Deviation, s
= 1.25
Sample size = 19
0April 3, 2008 at 4:14 am #170503
lonelysinParticipant@lonelysin Include @lonelysin in your post and this person will
be notified via email.Dear Pam,which formula you use to calculate the Power?
Also, how do you get 19?Thanks.0April 3, 2008 at 12:57 pm #170513
Engine LadyParticipant@EngineLady Include @EngineLady in your post and this person will
be notified via email.I was able to recreate what Pam’s answer was in Minitab.
Here are the steps:
Open Minitab
Click Stat / Power and Sample Size / 1sample t
In Differences field input a 1
In Power Values field input .95
In Standard Deviation Field input 1.25
Click Options Button in this same menu
Under Alternate Hypothesis Click Greater than radio button
Significance Level field input .05 if it is not already there by default
Click Ok and Ok
go to the minitab session window and you should see:
1Sample t Test
Testing mean = null (versus > null)
Calculating power for mean = null + difference Alpha = 0.05 Assumed standard deviation = 1.25
Sample Target
Difference Size Power Actual Power
1 19 0.95 0.956078
Hope this helps.
Engine Lady
0April 3, 2008 at 2:01 pm #170515Hi Engine,
I did work it out in Minitab, you reply sure helps. Any idea about the formula that is used to calculate the sample size?
Also I would like to caluclate the sample sizes for populations which do not follow a normal distribution, how is it calculated?0April 3, 2008 at 2:05 pm #170517
Engine LadyParticipant@EngineLady Include @EngineLady in your post and this person will
be notified via email.Hello: A search on Sample Size Formula will give you a lot of reference materials.
http://edis.ifas.ufl.edu/PD006
Here was one site when I did the search that may be helpful.
Engine Lady0 
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