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From |
Steven Samuels <sjsamuels@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: running simple regression on mixed data of cross-section and panel |

Date |
Tue, 7 Dec 2010 07:53:19 -0500 |

Steve On Dec 7, 2010, at 4:58 AM, Melaku Fekadu wrote: Hi Steven, Thanks again The weight of each individual is provided with the data and it takes into account the fact that some respondents are recurring. In other words, the weight for each individual is given so that the pooled sample remains representative. No problem with weighting samples. My questin is just what do you do when some of the observations are not independent to each other resulting from the recurrence of individuals (87% of the sample appear twice and 12% appear once). And this recurrence is not accidental? In this case, does xtreg helps?

Without going into the details of your particular data set, I urgeyou toconsult the study documentation . Weighting for such rotating studies really requires a very clear definition about what population eachindividual represents. You might well have to construct new weightsto doyour analysis. Perhaps the study documentation ,or publicationsbased onthe survey, will provide guidance; Otherwise, you will need to writeto thesurvey organization for advice. Steve Steven J. Samuels sjsamuels@gmail.com 18 Cantine's Island Saugerties NY 12477 USA Voice: 845-246-0774 Fax: 206-202-4783 On Dec 6, 2010, at 1:12 PM, Melaku Fekadu wrote: Hi Steve, Thanks for your help and here is a detail about the survey structure. The labor force survey is quarterly. In a given quarter, no individual appears more than once in the data. It is representative of the entire population and employment figures can be drawn from it. The survey returns to the same individuals in the subsequent quarters to be able to follow up their employment situation. The panel has a rotating structure: not all panels start at the same time. An example is given below. All in all, an individual should be interviewed in 4 quarters: in the first two consecutive quarters and in two more quarters after a spell of two quarters (with no interviews conducted) in between. For example, focusing about individuals who are interviewed in Q1 2009, as seen under Q1 bellow, they are composed of four types of individuals: 1) those who completed their final (fourth) interview in Q1. These individuals did their last 3 interviews in previous years 2) those who do their third interview in Q1. These individuals will do their final (fourth) interview in the next quarter, Q2, this year. They did their last 2 interviews in previous years. 3) those who do their second interview in Q1. These individuals will have a spell of 2 quarters (Q2 and Q3) with no interviews and will do their third interview in Q4, this year. They will do their last interview in Q1 of next year, 2010. 4) those who are interviewed for the first time in Q1. These individuals will do their second interview in Q2, this year. They will take a spell of two quarters (Q3 and Q4) with no interviews conducted. And then they will do their third and fourth interviews in the Q1 and Q2 of next year, 2010. Individuals who are interviewed in the other quarters of 2009 are also composed of four types of individuals with similar features. The problem of recurring individuals arises when I use a pooled data from 4 quarters. As we see the recurrence of respondents is not accidental. As seen bellow only 2/16 or 12.5% of the observations in the pooled data appear only once (those who are interviewed in Q1 their last – fourth – interview, and those who are interviewed in Q4 their first interview). The rest 87.5% appear twice. I would like to do my regressions in the pooled data of four quarters and I am afraid that this recurring feature of individuals has an impact on my regressions. My question is how do I take care of it? Does 'xtreg' helps? If so, I would appreciate any help on how to use xtreg. Year=2009 Q1 Q2 Q3 Q4 4 3 4 3 4 3 4 2 3 1 2 1 2 1 2 1On Sun, Dec 5, 2010 at 12:38 AM, Steven Samuels<sjsamuels@gmail.com> wrote:-- A panel survey is one which deliberately resurveys the same units. My guessis that you are talking about repeated independent samples of apopulationat different times. If not, please provide more details. If so, the chanceappearance of individuals in more than one survey is not anissue. UseStata survey commands, and incorporate "survey occasion" into thestratumdefinition for the -svyset- command. For most repeated surveys,the studydocumentation will give advice about this kind of issue. Steve Steven J. Samuels sjsamuels@gmail.com 18 Cantine's Island Saugerties NY 12477 USA Voice: 845-246-0774 Fax: 206-202-4783 On Dec 3, 2010, at 2:35 PM, Melaku Fekadu wrote: Dear all, I want to do a regression of employment (logistic) and wage (loglinear) on some demographic variables. I do the regressions on across-section data of labor force survey. However, small proportionofindividuals in the data recur more than once. How do I take into account the fact some people appear more than once in the data. Do I have to be concerned from running a simple regression? Thanks fekadu, * * 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/* * 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/

* * 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/

**Follow-Ups**:**Re: st: running simple regression on mixed data of cross-section and panel***From:*Melaku Fekadu <melaku.fekadu@gmail.com>

**References**:**st: running simple regression on mixed data of cross-section and panel***From:*Melaku Fekadu <melaku.fekadu@gmail.com>

**Re: st: running simple regression on mixed data of cross-section and panel***From:*Steven Samuels <sjsamuels@gmail.com>

**Re: st: running simple regression on mixed data of cross-section and panel***From:*Melaku Fekadu <melaku.fekadu@gmail.com>

**Re: st: running simple regression on mixed data of cross-section and panel***From:*Steven Samuels <sjsamuels@gmail.com>

**Re: st: running simple regression on mixed data of cross-section and panel***From:*Melaku Fekadu <melaku.fekadu@GMAIL.COM>

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