Many thanks for your response. 3. Too generic a question, it depends on what testing you're using. Sometimes you can back transform, other times you can't.- May I request you to tell me can we back transform for ANOVA test (or possibly parametric test) for my scenario listed above? ... View more

Thanks for your reply. My apologies for the follow up questions 2. Depends on what you mean. If you're testing by 2 different variables, i.e. 2 separate tests probably run two separate procs. If you're testing interaction of age and income, create an age-income variable and test via the new variable. The same proc NPAR1WAY is appropriate.-   When you say create an age-income variable , do you want me to concatenate both the variables? Because both are different indicators 3. If you're using non-parametric testing do you still need the transformation? - In case If I use parametric testing for other subjects, then how should I intrepret log normal transformation? Re: Normality Test ... View more

Any inputs on my questions? Thanks. ... View more

Many thanks for your reply. P value is <0.0001 with the below code proc npar1way wilcoxon  data=want; class new_age; var balance; run; Do we need to interpret only the P value from the output or anyother? Before I close this thread, I would like to clarify below. 1. From the documentation, there is no separate keyword for Kruskal-Wallis test. Am I right? WILCOXON requests an analysis of Wilcoxon scores. When there are two classification levels (samples), this option produces the Wilcoxon rank-sum test. For any number of classification levels, this option produces the Kruskal-Wallis test. See the section Wilcoxon Scores for more information. 2. In case if I wish to include 2 classification variables (age,income) in this test, which proc should I use? 3. With regards to normal and log-normal distribution, whether is any difference whilst interpreting the outputs? Because we're modifying the actual value to a log value of a independent variable. Thanks again for your inputs! ... View more

Then what should be the correct method? When I did non-parametric method with the code below, it takes hours to complete. After referring the documents, I understood that it works well for limited samples (say less than 1000) whereas my data has 25000 observations. proc npar1way wilcoxon data=want; class income; /* categorized into three levels*/ var balance1; exact; run; Any thoughts to re-direct me to obtain a normality or best fitted non-parametric procs? Thanks. ... View more

With the actual raw data mean is 5055 and the median is 68. Similarly skewness and kurtosis is 8.5 and 166 respectively followed by I did binning (15 bins) and removed the outliers. Now the mean is 14006.9 median is 14608.5 and skewness and kurtosis is 0.0013 and -1.2806 respectively. Considerably record count is reduced from 24000 to 600 where as p<0.001. Got a bell curve as well. Please suggest my final samples (600) is reasonably normal? Then I replaced the actual value of balance1 (or amount) to log value (via balance1=log(balance1) ) and then I did a log normal and it produced a bell curve alongside mean=median and skewness (0.2) is also similar to Kurtosis (-1.08). According to your advice, I tried to plot a Q-Q plot to check the normality with the code below. Attached the plot as well. Sounds it is non-normal as most of the data origin towards left. But I'm not very sure. ods graphics on; options maxmemquery=6M; proc univariate data=normality_new; QQPLOT balance1 / lognormal (sigma=2); /*I don't know about sigma value here*/ run; ods graphics off; So may I request you to view my plot and share your thoughts (or possibly verdict)? Thanks. ... View more

Thanks,will have a look at documentation for PROC NPAR1WAY. With regards to normality, I got a bell curve alongside mean=median and skewness (0.2) is also similar to Kurtosis (-1.08). but 'P' value is significant. e.g. p<0.001 So can we assume that our data is normal for the scenario as I mentioned above? or still we need to make it normal. I need to do ANOVA or GLM with that data. Thanks! ... View more

Can we make the inference in non-parametric test like we do in parametric test? e.g. I can test 'model balance=income age' in ANOVA or GLM. Since my data is non-normal how can I do the similar test in non-parametric approach? ... View more

I need to determine whether mean balance is different between groups. I agree with your point on 'If you remove some observations (0-s or outliers) your results (inference) will be valid only to a subpopulations. (For example you simply want to exclude accounts with 0 or very high balance, because they do not represent the “real wealth of the account owners”)'. Now I wondering what values should be replaced for negative and zero values for my variable 'balance' before applying log normal distribution? Because 25% of my data is less than or equal to zero. ... View more