[R-sig-Geo] Calculating median age for a group of US census blocks?

[Kevin Zembower]

Josiah, thanks for your reply.

Regarding my objective, I'm trying to compile census statistics for the 
blocks that make up the neighborhood where I live. It consists of ten 
census blocks, of which I selected three for simplicity in my example. 
The census block-group which contains these ten blocks also contains 
some blocks which are outside of my neighborhood and shouldn't be 
counted or included.

Since I won't be able to calculate the median age from the age and count 
data, and since the individual data doesn't seem to be available, is it 
your thought that I can't produce a valid median age for a group of 
census blocks?

Thanks so much for your advice.

-Kevin

On 8/7/23 14:38, Josiah Parry wrote:
> Hey Kevin, I don't think you're going to be able to get individual level 
> data from the US Census Bureau. The closest you may be able to get is 
> the current population survey (CPS) which I believe is also available 
> via tidycensus. Regarding your first question, I'm not sure I follow 
> what your objective is with it. I would use a geography of census block 
> groups as the measure of median for census block groups. Otherwise it is 
> unclear how you are defining what a "group of blocks" is.
> 
> On Mon, Aug 7, 2023 at 2:34 PM Kevin Zembower via R-sig-Geo 
> <r-sig-geo using r-project.org <mailto:r-sig-geo using r-project.org>> wrote:
> 
>     Hello, all,
> 
>     I'd like to obtain the median age for a population in a specific group
>     of US Decennial census blocks. Here's an example of the problem:
> 
>     ## Example of calculating median age of population in census blocks.
>     library(tidyverse)
>     library(tidycensus)
> 
>     counts <- get_decennial(
>           geography = "block",
>           state = "MD",
>           county = "Baltimore city",
>           table = "P1",
>           year = 2020,
>           sumfile = "dhc") %>%
>           mutate(NAME = NULL) %>%
>           filter(substr(GEOID, 6, 11) == "271101" &
>                  substr(GEOID, 12, 15) %in% c(3000, 3001, 3002)
>                  )
> 
>     ages <- get_decennial(
>           geography = "block",
>           state = "MD",
>           county = "Baltimore city",
>           table = "P13",
>           year = 2020,
>           sumfile = "dhc") %>%
>           mutate(NAME = NULL) %>%
>           filter(substr(GEOID, 6, 11) == "271101" &
>                  substr(GEOID, 12, 15) %in% c(3000, 3001, 3002)
>                  )
> 
>     I have two questions:
> 
>     1. Is it mathematically valid to multiply the population of a block by
>     the median age of that block (in other words, assign the median age to
>     each member of a block), then calculate the median of those numbers for
>     a group of blocks?
> 
>     2. Is raw data on the ages of individuals available anywhere else in
>     the
>     census data? I can find tables such as P12, that breaks down the
>     population by age ranges or bins, but can't find specific data of
>     counts
>     per age in years.
> 
>     Thanks for your advice and help.
> 
>     -Kevin
> 
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