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From |
Oliver Jones <ojones@wiwi.uni-bielefeld.de> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: plotting a regression function with time-dummies indicating structural breaks |

Date |
Tue, 03 May 2011 11:53:13 +0200 |

Hi Nick, here is some example I just made up, that shows what I mean by "range problem" ************* begin example **************** clear set obs 20 gen int TIME = _n + 1990 * create dummies gen byte d1 = 0 replace d1 = 1 if TIME > 1995 gen byte d2 = 0 replace d2 = 1 if TIME > 2005 tsset TIME * set coefficients scalar b_0 = 100 scalar b_1 = 2 scalar b_2 = 10000 scalar b_3 = -5 scalar b_4 = 20 * generate the time series set seed 1 gen u = rnormal(0,2) gen y = b_0 + b_1*TIME + b_2*d1 + b_3*d1*TIME + b_4*d2 + u tw /// (tsline y) /// (function y = b_0 + b_1*x + b_2*d1 + b_3*d1*x + b_4*d2, /// range(1991 2010)), /// legend(order(1 "tsline" 2 "function")) ************* end example **************** I hope the resulting plot shows what I mean. Best Oliver Am 03.05.2011 11:29, schrieb Nick Cox:

This is presumably a family of four curves given by a range on TIME_t and Dummy_1 = 0, 1 and Dummy_2 = 0,1. -twoway function- will take care of TIME_t = x but it is completely dumb about the dummies. My guess is that it will use Dummy_1[1] and Dummy_2[1] and give you just one of the four depending on values in the first observation. You will need to call -function- four times, but you don't need to type the code four times. Something like this: forval a = 0/1 { forval b = 0/1 { local fcall `fcall' (function y = b_0 + b_1*x + `a'*(b_2 + b_3*x) + b_4*`b', /// range(TIME_t)) } } twoway (tsline y) `fcall' , legend(order(2 "0 0" 3 "0 1" 4 "1 0" 5 "1 1")) I am assuming that this is generic code or that you have scalars b_0 .. b_4. By the way, the -generate- line is irrelevant. -twoway function- works with a generic x. On Tue, May 3, 2011 at 10:10 AM, Oliver Jones <ojones@wiwi.uni-bielefeld.de> wrote:I wonder if there is an easy way to plot a regression of the form: y_t = b_0 + b_1*TIME_t + Dummy_1*(b_2 + b_3*TIME_t) + b_4*Dummy_2 So far I tried: gen x = TIME_t twoway /// (tsline y) /// (function y = b_0 + b_1*x + Dummy_1*(b_2 + b_3*x) + b_4*Dummy_2, /// range(`first_year' `last_year')) I seem to have a problem with the range, because the resulting graph just covers one third of the graph. But the shape seems to look ok, just compressed. Hopefully there is a nice way of plotting such stuff without the -function- command or some one has a hint regarding the range problem.* * 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/

-- Universität Bielefeld Fakultät für Wirtschaftswissenschaften Lehrstuhl für Ökonometrie und Statistik - - Bielefeld University Faculty of Business Administration and Economics Chair of Econometrics and Statistics - - Raum / room: V9-110 Tel / phone: +49 (0)521 106 4871 --- * * 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/

**Follow-Ups**:**Re: st: plotting a regression function with time-dummies indicating structural breaks***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: plotting a regression function with time-dummies indicating structural breaks***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: plotting a regression function with time-dummies indicating structural breaks***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**st: plotting a regression function with time-dummies indicating structural breaks***From:*Oliver Jones <ojones@wiwi.uni-bielefeld.de>

**Re: st: plotting a regression function with time-dummies indicating structural breaks***From:*Nick Cox <njcoxstata@gmail.com>

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