Median Household Income in the SF Bay Area?

Question: What is the median household income in the nine-county San Francisco Bay Area?

Answer: The 2016 estimate of median household income in the twelve-county San Francisco Bay Area is $91,234, according to the 2016 American Community Survey conducted by the US Census Bureau.

Uh, the “twelve-county San Francisco Bay Area”? Well, it’s actually called the “San Jose-San Francisco-Oakland Combined Statistical Area.” The Combined Statistical Area, or CSA, is a creation of the US Office of Management and Budget (OMB) using population data collected by the US Bureau of the Census. The CSA is similar to the CMSA and the SCSA from bygone days. I’ll enlighten (and/or confuse) readers about these terms in future blog posts.

Metropolitan_and_Micropolitan_Statistical_Areas_(CBSAs)_of_the_United_States_and_Puerto_Rico,_Feb_2013.gif

The US Office of Management and Budget (OMB) is tasked with defining metropolitan areas in the United States and Puerto Rico. OMB relies on data from the US Census Bureau, and typically updates/overhauls these definitions once every decade using results from the previous decennial census (and American Community Survey data, as well.)

OMB has re-defined the greater San Francisco to now include (as of 2013) twelve (12) counties, starting with the “traditional” nine counties surrounding the San Francisco Bay and San Pablo Bay:

  1. Alameda County
  2. Contra Costa County
  3. Marin County
  4. Napa County
  5. San Francisco County
  6. San Mateo County
  7. Santa Clara County
  8. Solano County
  9. Sonoma County

After the 1980 Census, OMB added a tenth county to the Bay Area:

10. Santa Cruz County

After the 2000 Census, OMB added the eleventh county:

11. San Benito County

And finally, after the 2010 Census, OMB added county #12:

12. San Joaquin County

The reason and rationale for adding these additional counties to the traditional nine counties is based on commutation relationships between the adjacent counties and the central region. I think it’s about 15 percent-or-more of their resident commuters working in the central region, but I need to dig back through tiny print Federal Register notices to clarify this.

I downloaded data from the Census Bureau’s American Factfinder site on total population (Table B01003), total households (Table B25002) and median household income (Table B19013). Again, this is all for the single-year data from the 2016 American Community Survey.

The following table summarizes the population, households and median household income (2016) for the greater San Francisco Bay Area and its component metropolitan areas:

MSA/CSA Name Total Population,
2016
Total Households, 2016 Median Household Income, 2016
Napa, CA Metro Area 142,166 49,561 $75,077
San Francisco-Oakland-Hayward, CA Metro Area 4,679,166 1,691,781 $96,677
San Jose-Sunnyvale-Santa Clara, CA Metro Area 1,978,816 653,296 $110,040
Santa Cruz-Watsonville, CA Metro Area 274,673 96,257 $77,613
Santa Rosa, CA Metro Area 503,070 187,504 $73,929
Stockton-Lodi, CA Metro Area 733,709 227,186 $59,518
Vallejo-Fairfield, CA Metro Area 440,207 149,172 $73,900
San Jose-San Francisco-Oakland, CA CSA 8,751,807 3,054,757 $91,234

These component metropolitan areas, actually called “Metropolitan Statistical Areas” by the OMB/Census, are the areas that were reported by the Census Bureau and local media outlets this past week. These seven MSAs add up to the twelve-county “San Jose-San Francisco-Oakland Combined Statistical Area.”

So, the simplest answer to the “what is the median household income in the Bay Area” is $91,234. Half the households earn less than $91,234; and half the household earn more than $91,234. But this is for the twelve-county Bay Area. What about the nine-county Bay Area?

We (the public, journalists, government planners) don’t have access to the full set of ACS data to calculate the best estimate of median income for the nine-county Bay Area. The best (?) that can be done to is to approximate the answer using a “weighted means of the medians” for the relevant geographic areas.

This “weighted means of the medians” seems simple enough: multiply the total households by the median household income, then sum that product for all areas, then divide by the number of total households in all areas.

But the “weighted mean of the medians” for the seven component MSAs in the twelve-county region, is $93,312. That’s weirdly higher than the $91,234 value published by the Census Bureau. Maybe I’m missing something.

MSA/CSA Name TotalHH * Median HH Income Mean of Median
Napa, CA Metro Area $3,720,891,197
San Francisco-Oakland-Hayward, CA Metro Area $163,556,311,737
San Jose-Sunnyvale-Santa Clara, CA Metro Area $71,888,691,840
Santa Cruz-Watsonville, CA Metro Area $7,470,794,541
Santa Rosa, CA Metro Area $13,861,983,216
Stockton-Lodi, CA Metro Area $13,521,656,348
Vallejo-Fairfield, CA Metro Area $11,023,810,800
San Jose-San Francisco-Oakland, CA CSA $285,044,139,679 $93,312

Maybe some hotshot statistician can help me figure this out, given the data we all have access to.

That’s about all I have to say for today. I think I’ll blog about the ABCs of Metropolis in my next blog post: fun and games with SMA, SMSA, SCSA, PMSA, CMSA, CBSA, MSA, CSA and MD. Not to mention micropolitan areas.

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