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From |
"Wallace, John" <John_Wallace@affymetrix.com> |

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

Subject |
RE: st: RE: re: missing dummy variable |

Date |
Thu, 11 Oct 2007 09:54:36 -0700 |

Thanks very much, Kit and Maarten. This gives me a lot to think about. I hadn't missed Kit's first hints about lincom, I was just unsure about what to do with them. :) -JW -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten buis Sent: Thursday, October 11, 2007 8:09 AM To: statalist@hsphsun2.harvard.edu Subject: Re: st: RE: re: missing dummy variable --- Maarten buis <maartenbuis@yahoo.co.uk> wrote: > I think that the display of this many parameters would call for a > graph, so in the example below I show how I would add such > information together into one graph. A lot of the tricks I use are > explained here: > http://home.fsw.vu.nl/m.buis/wp/pvalue.html I have added some extra bells and wistles to the graph. I have probably added too many bells and wistles, but a) you can pick from this code whatever element you like, and b) it nicely illustrates that models focusing on the indidual means of the different groups or on deviatons from a refence group, or a grand mean are just the same model. Under normal surcomstances I would leave out the right y-axis and probably the confidence interval around the grand mean, but that would completely defeat the purpose of the original question. *------------------ begin example --------------- sysuse auto, clear gen domestic = !foreign rename make desc gen make = word( desc,1) tab make xi3: regress mpg e.make unab varlist : _I* local test : subinstr local varlist " _" " + _", all lincom -1*(`test') sort make by make : keep if _n == 1 keep make foreign mata b = st_matrix("e(b)")' // remove constant k = rows(b) - 1 b = b[1::k,1] // add dropped level b = st_numscalar("r(estimate)") \b V = st_matrix("e(V)") se = diagonal(cholesky(diag(V))) // remove constant se = se[1::k,1] // add droped level se = st_numscalar("r(se)") \ se df = st_numscalar("e(df_r)") ci = b :- invttail(df,0.025):*se, b :+ invttail(df,0.025):*se idx = st_addvar("float",("b","lb","ub")) st_store(.,idx,(b,ci)) end egen xaxis = axis(b), label(make) gen lb_mean = - invttail(e(df_r), 0.025) gen ub_mean = invttail(e(df_r), 0.025) gen mean = 0 forvalues mpg = 0(10)40 { local diff = `mpg' - _b[_cons] local newsc `"`newsc' `diff' "`mpg'" "' } local min = -_b[_cons] sum ub, meanonly local max = r(max) twoway rarea lb_mean ub_mean xaxis, color(gs14) || /* */ line mean xaxis, clstyle(solid) ||/* */ rcap ub lb xaxis || /* */ rcap ub lb xaxis, /* */ lpattern(blank) yaxis(2) || /* */ scatter b xaxis if foreign == 1, /* */ mcolor(red) msymbol(O) || /* */ scatter b xaxis if foreign == 0, /* */ mcolor(blue) msymbol(O) /* */ xlab(1/23,valuelabel angle(45)) /* */ xtitle("") /* */ ytitle("mpg", axis(1))/* */ ytitle("deviation from grand mean", axis(2)) /* */ yscale(range(`min' `max') axis(1)) /* */ yscale(range(`min' `max') axis(2)) /* */ ylab(`newsc', axis(1)) /* */ ylab(-20(10)20, axis(2)) /* */ xsize(7) /* */ legend(order(- "Grand mean" /* */ 1 "95%" "conf. int." /* */ 2 "mean" /* */ - " " /* */ - "By make" /* */ 3 "95%" "conf. int." /* */ 4 "foreign" /* */ 5 "domestic" ) /* */ position(4) cols(1)) *------------------ end example --------------- Hope this is useful, Maarten ----------------------------------------- Maarten L. Buis Department of Social Research Methodology Vrije Universiteit Amsterdam Boelelaan 1081 1081 HV Amsterdam The Netherlands visiting address: Buitenveldertselaan 3 (Metropolitan), room Z434 +31 20 5986715 http://home.fsw.vu.nl/m.buis/ ----------------------------------------- ___________________________________________________________ Want ideas for reducing your carbon footprint? Visit Yahoo! For Good http://uk.promotions.yahoo.com/forgood/environment.html * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**Re: st: RE: re: missing dummy variable***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**Re: st: RE: re: missing dummy variable***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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