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I have two independent groups who travel with different modes. I want to compare the distance traveled (which is a continuous variable) by different modes for these two groups. How do I compare them in SPSS? My sample size is small: each group has only 32 observations.


Sorry, I am a newbie in stats. Here is the actual question. I collected travel distance and the choice of travel mode in two different locations.

There are 32 people in each location with 6 different modes. Each person can choose one mode and give the travel distance.

My query is, how should I compare to see if the travel distances of these two groups are significantly different?

If it were categorical data, I could use chi square, but does the t-test work here?

I believe the t-test is to compare two groups with one mean in each group, but I have 6 $\times$ 2 separate mean values (one for the each mode and two locations). I hope I have made it clear now.

Thanks

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  • $\begingroup$ Your question title asks about "multiple" DVs, but I don't see anything like that in the question itself. Do you have just 1 DV (distance traveled), or are there others as well? $\endgroup$ – gung - Reinstate Monica Feb 9 '13 at 15:05
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    $\begingroup$ If you know that you want to use a t-test and are only asking how to conduct it with particular non-R software, then the question doesn't fit well with this site. $\endgroup$ – rolando2 Feb 9 '13 at 16:37
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    $\begingroup$ Distance travelled is unlikely to be well approximated by a normal distribution; it's likely to be highly right-skew. In that circumstance you might want to consider something other than a t-test. $\endgroup$ – Glen_b -Reinstate Monica May 22 '13 at 22:11
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Under the assumption that you have just one dependent variable (distance traveled), this can be assessed with a t-test. Be aware that one assumption for the t-test is that the variances (standard deviations) within the two conditions are equal. That might not be true for distances traveled using different modes of transportation. For example, a more convenient means of transportation might mean some people will travel further than they otherwise would, but people who want to make short trips will travel the same distance either way. If the variability is not the same, you should use Welch's t-test, which makes an adjustment to the degrees of freedom. If you are wondering how to do this in SPSS, this website looks helpful.

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