My aim is to discover whether a subsample of this dataset is representative of the larger sample (which includes the sub-sample). Hi Francesco. significance tests and confidence intervals. As far as the simple t-test goes, I disagree with the authors, as I really do not believe that the estimates a and c are independent. Its original implementation was provided by Baum (STB-57, 2000) and Baum and Sperling (STB-58, 2000). There are a few other key differences between the analysis of survey and non-survey data that you need to be aware of. • Note: a blank line must be included at the end of a WordPad do-file (otherwise last line will not run). - Should it be a t-test, theorically speaking, since the variance of the population is unknown? As it … The stata syntax is ttest read scr 650 c suppose. Subsample analyses. The Stata documentation says this may result in "may result in biased or inefficient estimates" but we don't have any guidance at this time as to the seriousness of the problem. 4. xtreg y1 x i.z xtreg y2 x i.z I want to check whether the βs are significantly different. In Stata. I learned that I have to run a Heterogeneity test first. Stata for Researchers: Statistics This is part five of the Stata for Researchers series. How do you test the equality of regression coefficients that are generated from two different regressions, estimated on two different samples? Allows larger files than do-file editor. The dfgls command is now part of official Stata. Returned Results. Why Stata Features New in Stata 16 Disciplines Stata/MP Which Stata is right for me? The Stata syntax is ttest read scr 650 c Suppose instead of the 420. Most statistical commands also save their results so that you can use them in subsequent commands. With two regular regressions I would use something like the following code in Stata to test a cross-equation restriction: sureg (y1 x ) (y2 x ) lincom [y1]x - [y2]x However Stata is explaining that this is not possible when I try to use xtreg. Date Fri, 11 Jul 2008 10:57:30 +0100 One is by doing a likelihood ratio test. You can just skip over most of these if you are content to trust Stata to do the calculations for you. Also, there are a lot of equations in the text, e.g. Stata. Statistics >Summaries, tables, and tests >Classical tests of hypotheses >t test (mean-comparison test) ttesti Statistics >Summaries, tables, and tests >Classical tests of hypotheses >t test calculator Description ttest performs ttests on the equality of means. mi estimate, esampvaryok: reg wage edu exp if race==1. Often, the same regression model is fitted to several subsamples and the question arises whether the effect of some of the explanatory variables, as expressed by the … But if a sample had a different proportion of high and low SES students, this number would be very different. I will follow up with another blog post and some code examples on how to do these tests in SPSS and Stata. I reshaped my data to long format, and declared it as panel data!! You could test whether several statistics that are descriptive of a distribution are the same in the subsample and the remaining sample. Stata has two subpopulation options that are very flexible and easy to use. In the first form, ttest tests that varname has a mean of #. Stata: Data Analysis and Statistical Software PRODUCTS. If the answer is Yes, read below… Good morning Guys! so I am using STATA to do so, But I don't get any results?? • We will use the Stata do-file editor to write do-files. Finally, there is an appendix that shows the equivalences between t-tests and one-way ANOVA with a regression model that only has dummy variables. If Y1 and Y2 are correlated in any way, then it seems to me that it would follow that regression coefficients for an explanatory variable (X1) for the two variables are going to be correlated as well. My "second" intuition was to conduct a normal t-test. Stata’s official website gives an example of the output: In this example, to test the equality of coefficients on x1 and x2, 6.06 and 2.80 are the F-stats that we are looking for. For completeness and just because, I also list two more ways to accomplish this test for the last example. 1.1.4 Added a reject()-option, as permute has it. Interval] -----+----- height | 3.189727 .1232367 25.883 0.000 2.905543 3.473912 _cons | 5.601677 8.930197 0.627 0.548 -14.99139 26.19475 ----- We can compare the regression coefficients of males with females to test the null hypothesis Ho: B f = B m , where B f is the regression coefficient for females, and B m is the regression coefficient for males. Supported platforms. I would like to formulate an answer like stated below: "T-tests showed that the subsample was healthier than the entire 2004 sample, which is reflected by lower scores on the dependent variable, ADL, IADL, mobility, self-assessed health and a higher score on cognitive ability."