For sample size calculation , when your sampling are convenience ,does it required attrition?

The error message is as follows:

However, the results are computed anyways.

It should be noted that the sample size in my groups is different.

I would appreciate your guidance.

Baset

Hello,

I have a statistical problem I need help with. But I can't find it anywhere

I did a test with 31 subjects and 3 treatments. Each subject underwent each treatment in a randomized manner. I constantly recorded the heart rate (over 2 hours)

For each treatment I calculated the mean heart rate for 17 time intervals (each 10 min) in order to observe the temporal development of the heart rate.

Now I would like to compare the measurement series with a 2 Factor ANOVA with repeated measurements. But I have the problem that the Mauchly test gives an epsilon value of 0,000 for treatment*interval and only a dot " . " for chi-square and significace, with df=527. How is this test result to be interpreted? And how do I proceed?

I would also be interested to know which test I can use if the treatment groups are not normally distributed. For another measurement I have the problem that in group A (treatment A) the normal distribution is not given at 1/17 intervals, in group B at 4/17 and in group C at 9/17. Also I only have 28 usable subject data sets for this measurement, so that I do not have more than 30 subjects.

Is the test robust enough for these injuries or what test do I need to take?

I would be eternally grateful if you could help me, as I have been trying to solve this problem for a long time now.

Kind regards,

Lukas

I'm analyzing my current research data for potential violations in statistical assumptions. The particular analysis/design in question is a 2 x 2 between-within (i.e., mixed design, repeated measures + between measure, etc.) factorial ANOVA. The problem I'm having (or maybe it isn't one?) is when I check for violations of the sphericity assumption. For whatever reason, whenever I run Mauchly's test of sphericity in SPSS, it gives me a Mauchly's W of 1.000, df 0, and Sig of . . Nothing...it gives me no sig. data. Why would that be?

Is it a sample size thing (my N = 34)?

Could it be due to largely unequal group sizes (n = 30 and n = 4 ) (note: I am well aware of the problems that my unequal group sizes have with regard to other assumptions and the reliability of any F statistic derived; I'm working on that problem but wanted to get an idea of how my data was looking)?

Maybe this means sphericity is as violated as it can be? The confusing thing is that I get the same result if I check sphericity with just the within measures in my control group of 30 participants. Any ideas why this might be? Please let me know if additional information or context is needed.

What is the good sample size for a pilot study questionnaire to ensuring precise data collection?

•However, some guidelines suggest that typical pilot sizes range from 5 to 20 participants, which may result in a very small precision.

•A common rule of thumb is to use a sample size of 10 to 20% of your full-scale survey sample size, or at least 30 to 50 respondents.

Which rule I should to follow?

Because I have already retested the questionnaire using 11 subjects, the reliability is high (Cronbach's Alpha= .774). However, the validity Degrees of Freedom is below the critical Pearson CC= 0.666. thanks for your concern.

I want to prepare a photocatalytic material Bi3TiNbO9 nanosheets and the authors mentioned NaCl-KCl (8 g), a molar ratio of 1:1 and an eutectic temperature of 657 °C as a one component. So, kindly explain this to me.

In my testing of statistical significance by bootstrapping, p_value shows that there are no specific indirect effects, but confidence intervals bias corrected 2.5% - 97.5% does not contain the value 0, this indirect effect has significance (followed source I read).

So there was a conflict and I wondered to use which result. Am I missing something?

The SLR paper that i submitted, the reviewers said that I just reiterated my results in discussion section. What else should i write besides comparing my finings with other similar and dissimilar studies.

Update 1: I have received the official RevMan installer links via email, which are still up on Cochrane's website.

Update 2: The links referred to above no longer work, as Cochrane have taken down the files, so I have removed them to avoid confusion. Please see Ingrid Arevalo-Rodriguez's answer below for further details.

Do NOT contact me via ResearchGate or otherwise about RevMan install files. I will NOT respond to you. Use RevMan web.

What is the equation used to calculate sample size in a community of 200000 -250000 people for a cross-sectional study using a questionnaire sheet.