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From |
"b. water" <barleywater@hotmail.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: R: which statistics to use |

Date |
Wed, 24 Mar 2010 00:42:40 +0000 |

dear Carlos, Thank you for your advice. I'll give this a go. bw > From: carlo.lazzaro@tiscalinet.it > To: statalist@hsphsun2.harvard.edu > CC: barleywater@hotmail.com > Subject: st: R: which statistics to use > Date: Mon, 22 Mar 2010 10:41:13 +0100 > > Dear b, > Though I am not sure if I am reading your data correctly (due to plain text > format), I would suggest an OLS with clustered standard error: > ................begin example................................... > set obs 12 > input concentration sample condition time id > .2 1 1 0 1 > .3 1 1 1 2 > .3 1 1 2 3 > .2 2 1 0 4 > .5 2 1 1 5 > .9 2 1 2 6 > .7 1 2 0 1 > .7 1 2 1 2 > .9 1 2 2 3 > .7 2 2 0 4 > 1.02 2 2 1 5 > 1.03 2 2 2 6 > end > regress concentration sample condition time, robust cluster(id) > Dr. Carlo Lazzaro > > Studio di economia sanitaria > > Via Stefanardo da Vimercate, 19 > > 20128 Milano > > tel/fax: 02 26000516 > > portatile: 335 6786741 > > e-mail: carlo.lazzaro@tin.it > > carlo.lazzaro@tiscalinet.it > > -----Messaggio originale----- > Da: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di b. water > Inviato: lunedì 22 marzo 2010 3.03 > A: statalist@hsphsun2.harvard.edu > Oggetto: st: which statistics to use > > Dear all, > > Stata 8.2, > > I have data consisting of serum concentrations measured at regular intervals > but under two different conditions (but a few missing reading here and > there) like so: > > > condition_1 condition_2 > t0 t1 t2 t0 t1 t2 > sample_1 0.2 0.3 0.3 0.2 0.5 0.9 > sample_2 0.7 0.7 0.9 0.7 1.2 1.3 > . > . > . > . > . > . > sample_n 0.3 0.5 0.6 0.3 0.8 1.1 > > Just 'eye-balling' the data I can see that condition_2 did affect the > concentrations. My questions: > > 1. How may I show that in condition_1 concentration at t1 and t2 _are_ > statistically different from t0 (if indeed they are). Had it been just t0 > with one other time interval, I would have thought of paired t-test off the > bat but don't what to do in this circumstances. It looks like ANOVA but > again would appreciate advice. > > 2. How may I show (statistically that is - and therefore what statistical > analyses I should deploy) that w.r.t. t1 and t2 that condition_2 IS > different from condition_1. > > Thank you for advice/help. > > bw > _________________________________________________________________ > Hotmail: Trusted email with powerful SPAM protection. > http://clk.atdmt.com/GBL/go/210850553/direct/01/ > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ _________________________________________________________________ Hotmail is redefining busy with tools for the New Busy. Get more from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID27925::T:WLMTAGL:ON:WL:en-US:WM_HMP:032010_2 * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: R: which statistics to use***From:*"Carlo Lazzaro" <carlo.lazzaro@tiscalinet.it>

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