I need to analyze US data from 1970 onwards. I'd like to use [https://usa.ipums.org](https://usa.ipums.org)   


Does anyone knows more about the 1970s samples? Is anyone of the following better than the other, or should I choose all of them?

* 1970 1% Form 1 State sample
* 1970 1% Form 2 State sample
* 1970 1% Form 1 Metro sample
* 1970 1% Form 2 Metro sample
* 1970 1% Form 1 Neighborhood sample
* 1970 1% Form 2 Neighborhood sample

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