I am using Stata for my analysis. I am analysing a numerical variable over a categorical one (with 3 groups). After confirming they are normally distributed, I did a one way ANOVA test. But Bartlett's test showed me that the variances are not equal. What should I do next? Do a Kruskal-Wallis test? Should I perform a multiple comparison test (Bonferroni) to confirm the association obtained frmm the one-way ANOVA test? Should I perform additional tests to the ANOVA one?
This is how my data looks like:
. oneway CH1_taumean TumorLocation if TissueType==1, bonferroni tabulate
| Summary of CH1_tau mean
Location | Mean Std. dev. Freq.
------------+------------------------------------
Right | 3.0568408 .35276463 18
Left | 3.3229682 .38533265 30
Rectum | 3.1543516 .67311474 15
------------+------------------------------------
Total | 3.206785 .46862096 63
Analysis of variance
Source SS df MS F Prob > F
------------------------------------------------------------------------
Between groups .850894138 2 .425447069 2.00 0.1443
Within groups 12.7646535 60 .212744225
------------------------------------------------------------------------
Total 13.6155476 62 .219605607
Bartlett's equal-variances test: chi2(2) = 8.7458 Prob>chi2 = 0.013
Comparison of CH1_tau mean by Location
(Bonferroni)
Row Mean-|
Col Mean | Right Left
---------+----------------------
Left | .266127
| 0.173
|
Rectum | .097511 -.168617
| 1.000 0.757
This is how my data looks like:
. oneway CH1_taumean TumorLocation if TissueType==1, bonferroni tabulate
| Summary of CH1_tau mean
Location | Mean Std. dev. Freq.
------------+------------------------------------
Right | 3.0568408 .35276463 18
Left | 3.3229682 .38533265 30
Rectum | 3.1543516 .67311474 15
------------+------------------------------------
Total | 3.206785 .46862096 63
Analysis of variance
Source SS df MS F Prob > F
------------------------------------------------------------------------
Between groups .850894138 2 .425447069 2.00 0.1443
Within groups 12.7646535 60 .212744225
------------------------------------------------------------------------
Total 13.6155476 62 .219605607
Bartlett's equal-variances test: chi2(2) = 8.7458 Prob>chi2 = 0.013
Comparison of CH1_tau mean by Location
(Bonferroni)
Row Mean-|
Col Mean | Right Left
---------+----------------------
Left | .266127
| 0.173
|
Rectum | .097511 -.168617
| 1.000 0.757
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