Hello everyone. I did an animal study with a total of 24 rats in four (4) different groups. I put 6 rats randomly in each group. Do I still need to calculate the sample size? Is it not straight forward that 24/4=6?
You would not use a paired t-test. Since the two groups are independent of each other, there are different people in each groups, you could use a Student’s or Welch’s t-test. A paired t-test is used only if your two groups are dependent or the same study participants are in both groups being compared. An example of a situation where you would use a paired t-test is if you measure blood pressure 1 hour before drinking coffee and then measure blood pressure 1 hour after drinking coffee. A paired t-test would be used to compare these two measurements since the same participants are measured in each group, before vs after.
Our Methodology Core looked into your question and provided the following response. "Under an integrative mixed methods (IMM) study, the determination of an appropriate sample size requires a broader integrative perspective: (a) that balances qualitative considerations favoring small manageable samples for conducting in-depth qualitative analyses (n = 20-40), against (b) quantitative considerations favoring larger sample sizes (n = 40-200) for conducting reliable multivariate statistical analyses." You may email command@sanfordhealth.org if you have additional questions.
A study that is interested in determining if a particular event occurs more often in one population compared to another (case vs control), needs to estimate P1 and P2. Estimating P1 and P2 is necessary to compute the sample size for comparing two independent proportions. These estimated proportions are typically determined from preliminary data, previous literature, or the researcher’s educated estimate. We hope this helps. If you have further questions, you can reach out to COMMAND@sanfordhealth.org
CRCAIH -Sanford thnks for ur answer See forexample i want to do a study about association between smoking and diabetes in bangladesh. So from where i can get proportions? Plz help this
I’m going to research on “the correlation between the levels of hs-CRP and mortality in acute ST elevation myocardial infarction” How can i calculate the sample size ? Which buttons in the software are to be chosen?
From our COMMAND core: Unfortunately, without more details on the study and research question it is difficult to give advice on which method you should be using for your sample size calculation. All I can really say is, decide on an analysis method (t-test, ANOVA, etc.), if you are using G-Power then go through the “Test family” and the “Statistical test” to find that method. You will then need to fill in the “Input Parameters” to calculate your sample size. G-Power also has a very helpful manual (www.gpower.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Psychologie/AAP/gpower/GPowerManual.pdf) that you could reference. If you are unsure of how to determine an analysis method and/or don’t know how to determine the input parameters, I would suggest getting assistance from a statistician.
excellent so clear thank you sooooo much
Thank you! That's the answer I was looking for :)
I do believe the *G- Power gives a better clear view of my sample size. Thank a lot for your input.
can i ask you one question for sample size?
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Hello everyone. I did an animal study with a total of 24 rats in four (4) different groups. I put 6 rats randomly in each group. Do I still need to calculate the sample size? Is it not straight forward that 24/4=6?
What formula used to calculate SD ? Please
how to find sample size for unknown pupulation
For the coffee example, should we use paired t test for sample size calculation?
You would not use a paired t-test. Since the two groups are independent of each other, there are different people in each groups, you could use a Student’s or Welch’s t-test. A paired t-test is used only if your two groups are dependent or the same study participants are in both groups being compared. An example of a situation where you would use a paired t-test is if you measure blood pressure 1 hour before drinking coffee and then measure blood pressure 1 hour after drinking coffee. A paired t-test would be used to compare these two measurements since the same participants are measured in each group, before vs after.
what application should i use for sample size determination of Quasi experimetal study pre test post test
Me too, I need the reponse in this question
what formula can one use if the outcome measure is both quantitative and qualitative?
Our Methodology Core looked into your question and provided the following response. "Under an integrative mixed methods (IMM) study, the determination of an appropriate sample size requires a broader integrative perspective: (a) that balances qualitative considerations favoring small manageable samples for conducting in-depth qualitative analyses (n = 20-40), against (b) quantitative considerations favoring larger sample sizes (n = 40-200) for conducting reliable multivariate statistical analyses." You may email command@sanfordhealth.org if you have additional questions.
Plz who can help me sample size calculation for case control study
I have confused how to get P1 and P2?
A study that is interested in determining if a particular event occurs more often in one population compared to another (case vs control), needs to estimate P1 and P2. Estimating P1 and P2 is necessary to compute the sample size for comparing two independent proportions. These estimated proportions are typically determined from preliminary data, previous literature, or the researcher’s educated estimate.
We hope this helps. If you have further questions, you can reach out to COMMAND@sanfordhealth.org
CRCAIH -Sanford thnks for ur answer
See forexample i want to do a study about association between smoking and diabetes in bangladesh. So from where i can get proportions? Plz help this
I’m going to research on “the correlation between the levels of hs-CRP and mortality in acute ST elevation myocardial infarction” How can i calculate the sample size ?
Which buttons in the software are to be chosen?
From our COMMAND core: Unfortunately, without more details on the study and research question it is difficult to give advice on which method you should be using for your sample size calculation. All I can really say is, decide on an analysis method (t-test, ANOVA, etc.), if you are using G-Power then go through the “Test family” and the “Statistical test” to find that method. You will then need to fill in the “Input Parameters” to calculate your sample size. G-Power also has a very helpful manual (www.gpower.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Psychologie/AAP/gpower/GPowerManual.pdf) that you could reference. If you are unsure of how to determine an analysis method and/or don’t know how to determine the input parameters, I would suggest getting assistance from a statistician.