What sample size is the required minimum?

- Thread starter tonip
- Start date

What sample size is the required minimum?

Hi Tonip,

Just to be sure, do you really have a treatment that improves both high blood pressure and low blood pressure? or do you mix 2 treatments?

The paired t-t test is equivalent to running the one sample t-test over the differences.

Technically you can try to calculate the improvement, and run one sample t-test over the improvement. (if meets the t-test assumptions)

before after improvement

30 40 10

40 38 -2

170 140 30

180 182 -2

But it doesn't feel right. Even if the same treatment does both... It is probably won't be normally distributed and not symmetric.

You try to achieve a sample size that will gain the test required power, usually 0.8

http://www.statskingdom.com/sample_size_all.html

Just to be sure, do you really have a treatment that improves both high blood pressure and low blood pressure? or do you mix 2 treatments?

The paired t-t test is equivalent to running the one sample t-test over the differences.

Technically you can try to calculate the improvement, and run one sample t-test over the improvement. (if meets the t-test assumptions)

before after improvement

30 40 10

40 38 -2

170 140 30

180 182 -2

But it doesn't feel right. Even if the same treatment does both... It is probably won't be normally distributed and not symmetric.

You try to achieve a sample size that will gain the test required power, usually 0.8

http://www.statskingdom.com/sample_size_all.html

Last edited:

Were ALL treated patients outside the 60-90 range before treatment?

And what is you clinical end point? Being in the 60-90 range after treatement (regardless of whether 60, 61, 70, 80, 89, or 90, for example)? Or perhaps something else, like "increase of heart rate by 10 or more, if the patient was < 60 before treatment".

With kind regards

Karabiner

Hi obh,

Thanks. Yeah, it's same treatment to improve heartrate.

Thanks. Yeah, it's same treatment to improve heartrate.

Regard the sample size, I think Karabiner that this was the question? . I assume you can start to calculate it base on the t distribution, and later check if it okay.