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Dear Statalisters,
I have done an economic experiment and want to compare the two groups in terms of median, mean and whether they are coming from the same population etc. I definitely do not feel comfortable about my knowledge about econometrics, so i need help about first what kind of tests are appropriate for my issue and how to interprete these tests. I really always confused about the wording in econometrics, such as ' we fail to reject the null hypothesis' So why dont we say that the null hypothesis is true, etc. In my study: Group A sample size is 17 Group B sample size is 18. What can you suggest me about possible tests? which one to choose? I did two of them allready,do you have more suggestions sich as KS test etc. And i dont know how to interprete the results, I looked at the manuels but really i cant be sure whether I understood it correctly or not. first one is median test, what is the formal name of this test in the literature, I can see from the command that it is testing the median but is there a formal name of the test which is related to the founders of the test, such as Man whitney. 1.). median offer, by(buyer) Median test Greater | than the | buyer median | 0 1 | Total -----------+----------------------+---------- no | 9 10 | 19 yes | 9 7 | 16 -----------+----------------------+---------- Total | 18 17 | 35 Pearson chi2(1) = 0.2743 Pr = 0.600 Continuity corrected: Pearson chi2(1) = 0.0340 Pr = 0.854 What does the Pearson and continutity corrected tell me, are the two medians different or not. Which one should I look, continutity correction or the one above. 2.)Another one is ranksum, but is this test same with U test, I am confused about the names, and the result interpretation ranksum offer, by(buyer) Two-sample Wilcoxon rank-sum (Mann-Whitney) test buyer | obs rank sum expected -------------+--------------------------------- 0 | 18 329 324 1 | 17 301 306 -------------+--------------------------------- combined | 35 630 630 unadjusted variance 918.00 adjustment for ties -9.26 ---------- adjusted variance 908.74 Ho: offer(buyer==0) = offer(buyer==1) z = 0.166 Prob > |z| = 0.8683 What does the results say, are they coming from different distributions or not? the means are different or not? Thank you very much in advance. |
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