What analysis is best for my research

#1
Hi all,

I'm currently doing my masters thesis about blood pressure monitors.
I'm compairing them on repeatability using a simulator.

Now i have 5 different devices with each 3 simulations x 85 measurements. (Simulations are High blood pressure, low and normal)
I did the basic thing like look at the mean values and standard deviations but want to go further.

What I already tried to do:

T-test;
I used excel to calculate this but the really really small;

1585162006150.png
Seems like I'm doing something wrong here.
Used my 2 columns in excel, two sided and coupled.. should be correct.

Bland Altman analysis;
Seems like my measurements are not different enough from one another to have a good analysis since i'm only getting 3 different points;

1585162229168.png

So my question to you guys is if somebody point me in the right direction on which analysis should be good for this research.
I've posted an example of my measurement of 1 device in attachement. (with no calculations on this one)

Thank you in advance!
 

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#3
The research question is:
What is the repeatability of the various commercially available blood pressure monitors.

For now I found the problem in my t-test in the upper message and i'm now having these kind of results;

1585388776691.png

Since the variance is liltle, my t-test doesn't give any good results.
For my research question these monitors are good (little variance) so I would need to use another type of test but I didn't find the right one yet.

Hope this makes it clearer, if not please let me know.