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, **statalist.org** is already up and running.

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

From |
David Hoaglin <dchoaglin@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Wed, 20 Mar 2013 15:14:58 -0400 |

Thanks, Nick. I was going to suggest a dotplot, but held off. The sample sizes are large enough that some jittering may be helpful. Preferences for plots may vary, but a thorough analysis should include graphical displays of the data. David Hoaglin On Wed, Mar 20, 2013 at 12:58 PM, Nick Cox <njcoxstata@gmail.com> wrote: > I wouldn't want to start with box plots here. For two groups, there is > space for more detail than a box plot gives, except capriciously in so > far as points are more than 1.5 IQR from the nearer quartile. > > I grew up, as it were, on box plots, including David's own writings 30 > or more years ago, but I think they are oversold in total. > > I have often seen -- even in otherwise good textbooks -- people > talking about t-tests or ANOVA and then giving box plots -- and not > even commenting on the mismatch, i.e. that the box plots are showing > medians etc., not means etc. > > A more directly relevant graph would, I suggest, be a dotplot (sensu > -dotplot-) or even -stripplot- (SSC). You can show means on such > plots. > > Nick * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Interpretation of Two-sample t test with equal variances?***From:*Gwinyai Masukume <parturitions@gmail.com>

**Re: st: Interpretation of Two-sample t test with equal variances?***From:*Richard Williams <richardwilliams.ndu@gmail.com>

**Re: st: Interpretation of Two-sample t test with equal variances?***From:*Gwinyai Masukume <parturitions@gmail.com>

**R: st: Interpretation of Two-sample t test with equal variances?***From:*"Carlo Lazzaro" <carlo.lazzaro@tiscalinet.it>

**Re: st: Interpretation of Two-sample t test with equal variances?***From:*Gwinyai Masukume <parturitions@gmail.com>

**Re: st: Interpretation of Two-sample t test with equal variances?***From:*David Hoaglin <dchoaglin@gmail.com>

**Re: st: Interpretation of Two-sample t test with equal variances?***From:*Nick Cox <njcoxstata@gmail.com>

- Prev by Date:
**st: While/if for individual observations** - Next by Date:
**Re: st: Interpretation of Two-sample t test with equal variances?** - Previous by thread:
**Re: st: Interpretation of Two-sample t test with equal variances?** - Next by thread:
**Re: st: Interpretation of Two-sample t test with equal variances?** - Index(es):