# Age at immigration calculation error

**URL:** <https://forum.ipums.org/t/age-at-immigration-calculation-error/4937>\
**Category:** USA\
**Created:** [October 26, 2022, 11:44pm UTC](https://forum.ipums.org/t/age-at-immigration-calculation-error/4937 "2022-10-26T23:44:07Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Hansa\_Sylvea](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hansa\_Sylvea](https://forum.ipums.org/u/Hansa_Sylvea)\
**Post date:** [October 26, 2022, 11:44pm UTC](https://forum.ipums.org/t/age-at-immigration-calculation-error/4937/1 "2022-10-26T23:44:07Z")

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for ACS data, I use BPL\>99 as a condition to choose immigrants and use (AGE - YRSUSA1) to get the age at immigration for immigrants. However, i get numbers like -6 and other negative numbers a lot! How could this be? is there more accurate way to do this?

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**Author:** ![Ivan\_Strahof](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/ivan_strahof/32/626_2.png) [@Ivan\_Strahof](https://forum.ipums.org/u/Ivan_Strahof)\
**Post date:** [November 4, 2022, 2:18pm UTC](https://forum.ipums.org/t/age-at-immigration-calculation-error/4937/2 "2022-11-04T14:18:03Z")

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I recommend taking a look[at this post](https://forum.ipums.org/t/yrsusa1-very-basic-question/4567) as this issue has been brought up in the past. In short, [YRSUSA1](https://usa.ipums.org/usa-action/variables/YRSUSA1#codes_section) in the ACS is derived from the year of immigration ([YRIMMIG](https://usa.ipums.org/usa-action/variables/YRIMMIG#description_section)), which can easily cause a difference of 1 year depending on their age and when they responded to the ACS. The other cases are likely related to aggregation and binning the oldest years together, which are not reflected in the labels for YRSUSA1. In the 2019 ACS for example, everyone who entered the US in 1929 or earlier would have their year of entry set at 1929. You can see how these years of entry are binned by taking a look at [US2019A\_YOEP](https://usa.ipums.org/usa-action/variables/US2019A_1075#description_section) and the other USXXXXA\_YOEP variables.

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**Author:** ![Hansa\_Sylvea](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hansa\_Sylvea](https://forum.ipums.org/u/Hansa_Sylvea)\
**Post date:** [November 5, 2022, 4:35am UTC](https://forum.ipums.org/t/age-at-immigration-calculation-error/4937/3 "2022-11-05T04:35:51Z")

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thanks for your reply, i counted the values below -2, and it turned out their number is rather small( a few hundred). So the error is acceptable