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From |
Steven Samuels <sjhsamuels@earthlink.net> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Stanard Error for Difference in Difference cross-tabulation |

Date |
Thu, 12 Feb 2009 09:45:48 -0500 |

-Steve On Feb 12, 2009, at 6:27 AM, Richard Palmer-Jones wrote:

Thanks for the replies, and sorry not to have been clearer and the delay in responding (student strike!) the variables are: label yearsedn "years of education" // cross section in 1999 gen old = born >= 1956 & born <= 1961 gen young = born >- 1970 & born <= 1975gen highintensity = state >= 5 & state <= 19 // states 1 -4 = lowintensitylabel highintensity "high primary school funding in 1976-81" //(i.e. treated)gen young_high = highintensity * young * Maarten suggests . reg yearsedn young highintensity young_high if young | oldSource | SS df MS Number ofobs = 2698-------------+------------------------------ F( 3,2694) = 115.81Model | 8584.36711 3 2861.4557 Prob >F = 0.0000Residual | 66562.2808 2694 24.7076024 R-squared = 0.1142-------------+------------------------------ Adj R-squared = 0.1132Total | 75146.6479 2697 27.8630508 RootMSE = 4.9707------------------------------------------------------------------------------yearsedn | Coef. Std. Err. t P>|t| [95%Conf. Interval]-------------+----------------------------------------------------------------young | 2.286417 .4506203 5.07 0.0001.40282 3.170013highintens~y | -3.533677 .3945928 -8.96 0.000-4.307412 -2.759941young_high | .7222411 .503475 1.43 0.152 -.2649952 1.709477_cons | 6.118812 .3497354 17.50 0.0005.433035 6.804589------------------------------------------------------------------------------I want a table with mean and standard errors of years of education where the Xs are in the following table, and the marginal differences young 0 1 difference _______________________________________ lo | X | X | X high | X | X | X _______________________________________ difference | X | X | X The row and column Xs can be filled in from calcuations of means (e.g in ttest), except for the bottom right X Maarten's suggestion is that the appropriate se is 0.503 Thanks for further help RIchard On Tue, Feb 10, 2009 at 5:18 PM, Steven Samuels <sjhsamuels@earthlink.net> wrote:While I agree with Maarten about the analysis procedure, I amunclear aboutthe design- does "one of which" in your description refer toregion or tocohort? Was there a treated cohort and a non-treated cohortwithin eachregion? Or, were there two cohorts within each region, but withtreatmentdiffering between region? Do you have a before/afterdifferences , or areall comparisons cross-sectional? Please lay out in more detail the design of the study -Steve--- On Tue, 10/2/09, Richard Palmer-Jones wrote:I want to calculate the standard error of the mean "diffference in difference". I have samples from two cohorts in each of two regions, one of which received a treatment, and their respective years of education; how to I calculate the standard error of the difference in difference of the years of education?Looks to me like an interaction effect: The dummy for cohort tells you how much the average education differs over cohorts, and you think that this difference differs across regions, so the interaction effect between cohort and region gives you this difference in difference, and -regress- will

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**Follow-Ups**:**Re: st: Stanard Error for Difference in Difference cross-tabulation***From:*Richard Palmer-Jones <richard.palmerjones@gmail.com>

**References**:**Re: st: Stanard Error for Difference in Difference cross-tabulation***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**Re: st: Stanard Error for Difference in Difference cross-tabulation***From:*Steven Samuels <sjhsamuels@earthlink.net>

**Re: st: Stanard Error for Difference in Difference cross-tabulation***From:*Richard Palmer-Jones <richard.palmerjones@gmail.com>

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