Timeline for Mann-Whitney or t-test to compare age and expenditure after clustering
Current License: CC BY-SA 3.0
20 events
| when toggle format | what | by | license | comment | |
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| Jul 11, 2013 at 15:58 | vote | accept | Cesare Camestre | ||
| Jul 11, 2013 at 15:58 | vote | accept | Cesare Camestre | ||
| Jul 11, 2013 at 15:58 | |||||
| Jul 11, 2013 at 13:47 | vote | accept | Cesare Camestre | ||
| Jul 11, 2013 at 15:58 | |||||
| Jul 11, 2013 at 13:46 | vote | accept | Cesare Camestre | ||
| Jul 11, 2013 at 13:47 | |||||
| Jul 11, 2013 at 12:40 | comment | added | Cesare Camestre | Its not a matter of making a decisions. I just want to gather views as to wether i should use the Mann Whitney or the the t | |
| Jul 11, 2013 at 12:15 | comment | added | Gala | @IdiotAbroad I implicitly suggested you look at them… I can't just make the decision for you, without knowing about the project, over some Internet Q&A site. | |
| Jul 11, 2013 at 12:12 | comment | added | Cesare Camestre | Gael, I updated the posts and posted some of the plots you suggested. Of concern is probably the box plot of age in cluster 1. | |
| Jul 11, 2013 at 11:51 | history | edited | Gala | CC BY-SA 3.0 |
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| Jul 11, 2013 at 11:46 | comment | added | Gala | Not sure what to make of this last plot. This variable seems in fact discrete but not so bad, considering. Your last edit suggests that by “non-normal”, you mean you rejected normality in some test; I don't think it matters in the least. In any case, what I would look at are density plots, boxplots or stripcharts of each group/cluster, looking for differences in the shape or variance of the distribution. | |
| Jul 11, 2013 at 11:35 | history | edited | Gala | CC BY-SA 3.0 |
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| Jul 11, 2013 at 11:35 | comment | added | Cesare Camestre | The practical recommendations, where what I was after. As to your comment that that t-test might still be fine, I posted a q-norm plot of age, if that helps in anyway to give some more insight. | |
| Jul 11, 2013 at 11:30 | history | edited | Gala | CC BY-SA 3.0 |
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| Jul 11, 2013 at 11:12 | comment | added | Cesare Camestre | I do understand your points here. Let me clarify that these are not the main predictors in the cluster analysis. A priori I would expect differences in the means of these two sub-samples (based on literature). Now given that age does not follow normal distribution - what is the suggestion here. | |
| Jul 11, 2013 at 11:06 | comment | added | Gala | @IdiotAbroad What I mean is that the larger it is, the “nicer” the sampling distribution of the mean even if the distribution of the data is non-normal. It's probably impossible to provide a hard-and-fast threshold which is why you will find a lot of these confusing noncommittal recommendations. | |
| Jul 11, 2013 at 11:02 | comment | added | Nick Cox | @Peter Flom. Glad you agree, but you mean complementary... Insert emoticon if desired. | |
| Jul 11, 2013 at 10:59 | comment | added | Gala | @NickCox Yes, indeed, but I forgot to mention the fact that Mann-Whitney U compares different hypotheses than the t-test and is not a drop-in “non-parametric” replacement for it as it is sometimes presented, an important point as well. | |
| Jul 11, 2013 at 10:58 | comment | added | Cesare Camestre | - I did conduct a search but specific answers to my questions were not provided - Point 2 re t test assumptions, - always confused by what you mean by larger samples, each sample has around 300 items in it - Point 3 was a quote from the Handbook of Parametric and Non Paramtric Stats by sheskin. | |
| Jul 11, 2013 at 10:55 | comment | added | Peter Flom | All three of us were writing at the same time! And all three answers are consistent and somewhat complimentary. | |
| Jul 11, 2013 at 10:51 | comment | added | Nick Cox | This answer and mine were being written simultaneously. They look entirely consistent to me. | |
| Jul 11, 2013 at 10:49 | history | answered | Gala | CC BY-SA 3.0 |