Hi Izidine, On Friday, 20. August 2010 15:19:24 Izidine Pinto wrote: > Dear R users > I am using KS test to compare two different distribution for the same > variable (temperature) for two different time periods. > H0: the two distributions are equal > H1: the two distributions are different > > ks.test (temp12, temp22) > > Two-sample Kolmogorov-Smirnov test > > data: temp12 and temp22
This tells you where the data comes from that was used in this test, basically the program-variable you assigned the values to. > D = 0.2047, p-value < 2.2e-16 D represents the value of the test-statistic (difference), so the KS-statistic and the p-value represents the likelihood of observing this particular value of D, or a "more extreme" value by pure chance. > alternative hypothesis: two-sided > > Warning message: > In ks.test(temp12, temp22) : cannot compute correct p-values with ties This tells you, that ties occured when performing the test. A "tie" means that two or more samples had the same value. The problem with ties is basically, that it results in difficulties calculating the variance of your variable. Some tests account for this by calculating exact p-values based on permutations, which is, especially for larger sample sizes, computationally expensive. > I don't rally know how to interpret the output from R. I don't want to judge your skills on statistics. However, it seems to me, that you are not completely familiar with the concept of hypothesis testing, the applied statistical tests and the interpretation of the results. Understanding what the test statistic and p-value (confidence interval etc.) are is fundamental for any subsequent steps, especially the interpretation of the calculated results. I had to learn this personally only recently ;) After all, R is just a tool, but the concepts behind the methods it offers must be understood separately as they are basic statistics most of the time. > Any help is appreciated. > > ** Hope that makes it a bite more clear. Otherwise, please feel free to ask further :) > > [[alternative HTML version deleted]] > Best, Cedric > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html and provide commented, > minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
