Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: st: Interpretation of Two-sample t test with equal variances?

From   "JVerkuilen (Gmail)" <>
Subject   Re: st: Interpretation of Two-sample t test with equal variances?
Date   Wed, 20 Mar 2013 20:45:10 -0400

On Wed, Mar 20, 2013 at 7:50 PM, David Hoaglin <> wrote:
> Jay,
> If the way people teach boxplots is the (main) source of the
> difficulty, I would not be inclined to blame the boxplot!


> I'm not sure what you mean by "the box ends up being too big" if the
> data are light-tailed.  I would expect the "whiskers" to be unusually
> short.

That was my way of saying that the whiskers were too short.

> A boxplot can do only so much.  The display was not designed to reveal
> bimodal or multimodal data.  A dotplot would usually show that
> structure easily.

Graphics, by their very nature, make assumptions about the data
because they provide data reduction. The boxplot provides a lot of
data reduction as it takes a variable from N observations down to 5
plus a few. So the boxplot's key assumption is that the data are

I guess I agree with Nick that they've been oversold, but as I say I use them.
*   For searches and help try:

© Copyright 1996–2016 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index