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Thread: Unequal variances in ANOVA

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    Unequal variances in ANOVA




    Non-statistician here, looking for help...

    My data (data from 8 different populations of plants) when analyzed using one-way ANOVA on SPSS v21 shows that the variances are unequal so the one-way ANOVA can't proceed and I also can't accept Tukey's multiple range comparisons.

    Transformation of the data using Square Root, ArcSin(SqRt), log, etc. does not resolve the issue of unequal variances. So, what analysis would you recommend in this case? I would like to be able to conduct multiple comparisons of the data while solving the unequal variance issue. I've heard of the Welch test but am unsure if this would be useable in my case. I only have access to SPS v21.
    Thanks

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    Re: Unequal variances in ANOVA

    So the test won't run is SPSS, citing unequal variance?


    The non-parametric analog to ANOVA is the Kruskal Wallis, followed up with multiple comparisons using Wilcoxon rank sum tests.
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    Re: Unequal variances in ANOVA


    So, what analysis would you recommend in this case? I would like to be able to conduct multiple comparisons of the data while solving the unequal variance issue. I've heard of the Welch test but am unsure if this would be useable in my case. I only have access to SPS v21.
    They've got "options" in the SPSS menues, and help functions also.
    In SPSS oneway there surely are procedures for unequal variances.

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