jamovi

Hi Team,

Love the product, but I was surprised the built-in one-way ANOVA doesn't currently have an effect size for the main effect (omega^2 or eta^2). I can get the values under the regular ANOVA, but sometimes I have to run a few one-way and it'd be easier to do that all in one menu.

Keep up the great work though!

I hear ya. It would be nice to have an effect size option from the one-way ANOVA menu. That said, a one-way analysis using the ANOVA menu provides the same results, a more detailed summary table, and options for effect size.

Hi,

I agree that it'd be great to get effect size into the one-way ANOVA menu and I've been instructing students to just use the ANOVA menu instead for that. BUT I could just switch them entirely to the ANOVA menu and ignore the one-way ANOVA menu, if only the ANOVA menu offered the choice of fisher's vs welch's - it already offers the assumption checks that necessitate that choice but not the choice itself. Instead we're in the situation that neither route through the analysis offers all the choices the student needs to make/values they need to report.

While a Fisher's (i.e., equal-variance) one-way ANOVA is identical whether one uses the one-way dialog or the non-oneway dialog. But Welch's (i.e., unequal variance) ANOVA is different and is not represented in the non-oneway ANOVA dialog. I have questions about how one ought to conceptualize and compute an effect-size for a Welch's one-way ANOVA.

If only there was a fisher's vs. welch's option on the ANOVA menu; it currently provides the assumption checks that call for that decision, but not the option itself.

Putting a Fisher's vs Welch option on the ANOVA menu would present a problem: There's no such thing as a multi-factor Welch's ANOVA. Mathematically, Welch's is only an option for single factor ANOVAs.

Also, the GUI for the oneway ANOVA does include the option to perform tests of assumptions.

That's what I thought. It would be helpful if the one-way ANOVA drop-down menu included a choice for effect size. However, the same information can be obtained by a one-way analysis using the ANOVA menu, with the added bonuses of a more thorough summary table and effect size adjustment possibilities.
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@vacantbottle
I think the only reason to have a one-way ANOVA option is as a means to conduct Welch's ANOVA. However, I'm not aware of ay consensus about the proper way to quantify the effect-size for a Welch's ANOVA. Consequently I see why it's reasonable, at the preset time, to exclude effect-size from the output of the one-way ANOVA. Furthermore, in the menu, maybe it would be a conceptual improvement to change the title "One-Way ANOVA" to "Welch's One-Way ANOVA," and to not include Fisher's ANOVA there.