Hello Fatima,

Except for discrepancies introduced by rounding error in the provision of summary statistics, the two methods are identical. The usual independent samples t-test can be (and is typically) applied by entering raw data for the two batches. However, you can also derive the t-statistic by having the mean, SD (or variance) and sample size for each of the two tests (this is the so-called summary independent samples t-test).

Good luck with your work.

so what is the more accurate in your opinion ?

I think summary will be more accurate for small samples ?

David Morse so what is the more accurate in your opinion ? I think summary will be more accurate for small samples ?

thank you very much

Dear Fatima Alhamed Alduihi , the two were misconcepted as different. They refer to the same test, Student's t Test for Significance difference between two independent sample's summary Statistics. An example of research question it can answer :"Can the scientist conclude, with a 95% confidence interval, that her trials on stander and patient does not results into statistically different results/means (extendable to proportion too)? Except you are referring to a single sample t test or Pre-Post Test or Paired 2 Sample Test. This test is also known as: Independent t Test, Independent Measures t Test, Independent Two-sample t Test, Student t Test, Two-Sample t Test, Uncorrelated Scores t Test, Unpaired t Test.

Note: A paired t-test is used when we are interested in the difference between two variables(e.g. Pre-Post intervention) for the same subjects(or patients).

Jochen Wilhelm

@Fatima, thankyou so much for this observations. I think they are not the same, the questions and procedures! The independent-samples t-test (or independent t-test, for short) compares the means between two unrelated groups(of treatment or intervention, A& B nested as the IV) on the same continuous, dependent variable, DV. See https://www.google.com/url?sa=t&source=web&rct=j&url=https://statistics.laerd.com/spss-tutorials/independent-t-test-using-spss-statistics.php&ved=2ahUKEwju5dT-36LsAhUScBQKHZIJAskQFjALegQIAxAB&usg=AOvVaw2pd7gWlxRrlKto7J01vpEM

Whereas, Summary two sample t test, test two independent samples(no IV or DV) but their summary Statistics (mean) for inferential Statistical difference.

See pictures attached

if I have a trial on 2 groups (patients and stander) and I want to compare the means of serum concentrations of one test (crp for example) , then what is the appropriate ?

In case we apply (before and after, we usually use t independent test)

In case of trials on mice they apply t student ! the formula is the same of summary , so do they are the same or not ? what is the difference between the 2 methods ?

Jochen Wilhelm