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From |
David Airey <david.airey@Vanderbilt.Edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: Nonparametric test |

Date |
Tue, 7 Oct 2008 11:24:16 -0500 |

-Dave On Oct 7, 2008, at 10:37 AM, Steven Samuels wrote:

Unless you took care to identify all the person you could havesampled, and you ensured each of those persons had an equallikelihood of being sampled, it doesn't sound to me like you are ina position to use survey statistics.Nigussie may have have survey data even if neither of theseconditions are true:1) Rarely do surveys have a list of individuals who could have beensampled. Simple case: a three stage area sample: 1. blocks; 2.households, 3. individuals. The first list is a list of blocks.After units are drawn at one stage, only units eligible for drawingat the next stage are listed.2) Most multi-stage samples do not maintain equal probabilities ofselection for the last stage units. It can be done, however. Forexample, an area sample can make the probability of selecting eachhousehold the same. If information is gathered from or about allindividuals in a household, each will inherit the household'sprobability.-Steve On Oct 7, 2008, at 10:22 AM, David Airey wrote:But maybe here is a case where the person asking the question isnot familiar with statistics generally? Any answer might behelpful. Advice given here is just advice, and there is no promiseit is correct.If you have a table of two categorical variables (e.g., country andincome group) and you can make a table of frequencies of eachcountry and income group combination, a chi-square statistic is oneway to ask if there is an association between the two variables. Itis a nonparametric test.A confusing aspect of your presentation is the variable individual,that it is numbered in a way that suggests the same individual isin multiple countries, and that your are talking about pairedanalyses. That may throw off people into thinking your design ismore complicated than it really is. My guess is you have a simplelisting of different people from different countries withassociated incomes. Unless you took care to identify all the personyou could have sampled, and you ensured each of those persons hadan equal likelihood of being sampled, it doesn't sound to me likeyou are in a position to use survey statistics.See the command -tabulate twoway- for a simple solution. See the command -survey- if I'm wrong. -Dave On Oct 7, 2008, at 7:22 AM, Nick Cox wrote:Your data structure is now clear. Thanks for that.I remain totally in the dark on what kind of test and what kind ofhypothesis you have in mind. You ask for a paried test but even aguess that that is a typo for paired does not help me as I do notsee here a paired comparison of any kind.What's more, advice is difficult if not foolish in the absence ofinformation on survey design.Sorry not to be able to add more, but you didn't answer severalquestions in my earlier post.Naturally this doesn't inhibit others from answering your question. Nick n.j.cox@durham.ac.uk nigussie TeferaI am very sorry for stating my question in an ambiguous form.Here, is an examplecountry individual income group x 1 2 x 2 1 x 3 2 x 4 3 . . . . . . . . . y 1 1 y 2 3 y 3 1 y 4 2 . . . . . . . . . y 1 3 y 2 2 y 3 1 y 4 1 . . . . . . . . .Now I want to generate the following table with paried test(compared all countries)Income group countryX yz w paried test1 count count countcount ?2 count count countcount ?3 count count countcount ?If I want to fill all ? (question marks) what stata command shouldI use? Note: I have no problem in producing count. By the way,count can be either row or column percentages. I hope this willclarify the issuesNick Cox <n.j.cox@durham.ac.uk>I don't get a clear picture of what your data look like. We havecountries, groups and individuals floating around in perfectfuzziness. Let me try again.1. Do your data look like this? i.e. one observation, one country. Country Income group x 1 y 2 z 2 w 32. Or do you have replicates (e.g. areas, individuals) within eachcountry?i.e. several observations for each country. 3. Or do you have something else? If so, give an example. Please answer: 1, 2 or 3.Also, what do you mean when you say that you want a separate testfor each income group?No difference in what? Nick n.j.cox@durham.ac.uk nigussie Tefera Many thanks!My data looks like eactly what you stated but country x has high,middle and low income groups (individuals) and the same is appliedfor country y, z and w. Now, I want to test, whether there isstatistically significant difference among high income groupsacross countries. The same is also true for mindle and low incomegroups. In short: the null hypothesis is no difference amongcountries for low, middle and high income groups (I need separatetest for each income groups)Nick Cox <n.j.cox@durham.ac.uk> These are your variables, but what is your data structure? Do your data look like this? Country Income group x 1 y 2 z 2 w 3Or do you have replicates (e.g. areas, individuals) within eachcountry?And what hypothesis are you testing? nigussie TeferaI have two categorical variables: namely incomecat (1=high,2=middle and 3=low income) and country ( labeled as (x, y, z, w)).Suppose that each country has high, middle and low income group.If I want to run paired test for each income group acrosscountries, what stata command should I use?* * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/* * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/* * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**Re: st: RE: Nonparametric test***From:*nigussie Tefera <nitefera@yahoo.com>

**RE: st: RE: Nonparametric test***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Nonparametric test***From:*David Airey <david.airey@Vanderbilt.Edu>

**Re: st: RE: Nonparametric test***From:*Steven Samuels <sjhsamuels@earthlink.net>

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