[R-sig-Geo] Calculating median age for a group of US census blocks?
Kevin Zembower
kev|n @end|ng |rom zembower@org
Tue Aug 8 21:31:50 CEST 2023
Dexter, Thanks so much for your reply. I wasn't aware of the two sources
you cite, and I'll be sure to include them in my work.
The open Baltimore website, at
https://data.baltimorecity.gov/datasets/neighborhood-1/explore, has
statistics for my neighborhood, Radnor-Winston
(https://radnorwinston.org).The Baltimore Neighborhood Indicators
Alliance at https://bniajfi.org/vital_signs/ lumps us into North
Baltimore/Guilford/Homeland, which, as I'm sure you're aware, contains
many homes (mansions!) with very different characteristics than the
people of Radnor-Winston.
Thanks, again, for your help and expertise. I learned a lot from your note.
-Kevin
On 8/7/23 15:43, Dexter Locke wrote:
> Hi Kevin and all,
>
> Given the binned data, you could count the number of people per age
> class for those 10 blocks. You can then express that in a number of
> different ways, like percent under 25 years old, or by calculating the
> dependency ratio
> <https://www.who.int/data/gho/indicator-metadata-registry/imr-details/1119#:~:text=Definition%3A,a%20specific%20point%20in%20time.>.
>
> I do think it is feasible to calculate an estimated mean from the counts
> within groups representing ranges. See, for example, here:
> https://stackoverflow.com/questions/18887382/how-to-calculate-the-median-on-grouped-dataset <https://stackoverflow.com/questions/18887382/how-to-calculate-the-median-on-grouped-dataset>
>
> Since you are working in Baltimore, you may consider looking at The
> Baltimore Neighborhood Indicators Alliance
> https://bniajfi.org/vital_signs/ <https://bniajfi.org/vital_signs/>.
> They provide useful data on a range of issues (transportation, crime,
> education, environment etc.) including summaries from Census-derived
> demographics. What you are seeking may already exist. BNIA creates
> neighborhoods or "community statistical areas" (n=55) based on
> aggregates of Census data.
>
> Although not pertaining to age, Baltimore City Planning has paid Census
> in the past to aggregate from individual-level Census data to the more
> colloquially-used definitions of Baltimore shown here (n = 273):
> https://data.baltimorecity.gov/datasets/neighborhood-1/explore?location=39.284832%2C-76.620516%2C12.91 <https://data.baltimorecity.gov/datasets/neighborhood-1/explore?location=39.284832%2C-76.620516%2C12.91>
>
> Best, Dexter
> https://dexterlocke.com/ <https://dexterlocke.com/>
>
>
>
>
>
> On Mon, Aug 7, 2023 at 3:02 PM Kevin Zembower via R-sig-Geo
> <r-sig-geo using r-project.org <mailto:r-sig-geo using r-project.org>> wrote:
>
> 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>
> <mailto: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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