# It is a good idea to pool the 1970 form 1 metro sample and 1970 form 2 metro sample together

**URL:** <https://forum.ipums.org/t/it-is-a-good-idea-to-pool-the-1970-form-1-metro-sample-and-1970-form-2-metro-sample-together/2047>\
**Category:** USA\
**Created:** [November 29, 2017, 10:47pm UTC](https://forum.ipums.org/t/it-is-a-good-idea-to-pool-the-1970-form-1-metro-sample-and-1970-form-2-metro-sample-together/2047 "2017-11-29T22:47:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Vera](https://avatars.discourse-cdn.com/v4/letter/v/b3f665/32.png) [@Vera](https://forum.ipums.org/u/Vera)\
**Post date:** [November 29, 2017, 10:47pm UTC](https://forum.ipums.org/t/it-is-a-good-idea-to-pool-the-1970-form-1-metro-sample-and-1970-form-2-metro-sample-together/2047/1 "2017-11-29T22:47:00Z")

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Hi there,

I am trying to calculate house prices for all metropolitan areas. Therefore I would like to have as many observations as possible for each metropolitan areas in each year. Do you think it is plausible to pool the 1970 form 1 metro sample and 1970 form 2 metro sample together and use the weight (hhwt) to calculate the mean(median) house price for each metropolitan areas?

Thanks a lot.

All my best,

Vera

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**Author:** ![JeffBloem](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/jeffbloem/32/40_2.png) [@JeffBloem](https://forum.ipums.org/u/JeffBloem)\
**Post date:** [November 30, 2017, 2:23pm UTC](https://forum.ipums.org/t/it-is-a-good-idea-to-pool-the-1970-form-1-metro-sample-and-1970-form-2-metro-sample-together/2047/2 "2017-11-30T14:23:00Z")

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It is reasonable to combine the two 1970 metro samples in order to create a larger data set. This is possible because these samples are, for all practical purposes, mutually exclusive. See page 8 of the [1970 codebook](https://usa.ipums.org/usa/resources/codebooks/1970_PUMS_codebook.pdf) for a discussion of this fact. Note, however, that the household weight ([HHWT](https://usa.ipums.org/usa-action/variables/HHWT#description_section)) is designed so that each of these samples, individually, represents the entire population. So, you will have to adjust the sampling weight in some way. A reasonable way to do this is to simply divide the weight variable by the number of samples you are pooling together. So, in your case you should generate a new weight variable that is equal to HHWT divided by 2.

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**Author:** ![Chris\_B](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Chris\_B](https://forum.ipums.org/u/Chris_B)\
**Post date:** [March 24, 2023, 5:47am UTC](https://forum.ipums.org/t/it-is-a-good-idea-to-pool-the-1970-form-1-metro-sample-and-1970-form-2-metro-sample-together/2047/3 "2023-03-24T05:47:14Z")

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I saw some strange-looking numbers from this pooled sample, after laboring a bit I grew this hunch that I would need to exactly what you said. Just wanted to drop a reply thanking you for confirming this solution and saving me a headache!