Question

The data is available free from the IRS for income data by zip code for 2008.

A00100 is the Adjusted Gross Income (aka AGI), agi_class is the size of the adjusted gross income. This ranges from 1 to 7:

1 = 'Under $10,000'
2 = '$10,000 under $25,000'
3 = '$25,000 under $50,000'
4 = '$50,000 under $75,000'
5 = '$75,000 under $100,000'
6 = '$100,000 under $200,000'
7 = '$200,000 or more '

“Number of Returns” is the Number of tax returns for that agi_class.

mysql> select A00100,zipcode,agi_class,N1 as 'Number of Returns' from taxbyzip2008 where     zipcode="10021";
+-------------+---------+-----------+-------------------+
| A00100      | zipcode | agi_class | Number of Returns |
+-------------+---------+-----------+-------------------+
|     -954234 | 10021   |         1 |              3589 |
|    43243455 | 10021   |         2 |              2521 |
|   149940475 | 10021   |         3 |              3939 |
|   243853640 | 10021   |         4 |              3936 |
|   262995399 | 10021   |         5 |              3025 |
|   751195421 | 10021   |         6 |              5333 |
| 10677437299 | 10021   |         7 |              7477 |
+-------------+---------+-----------+-------------------+

I need to come up with the Average Adjusted Gross Income for each zip code. How can I do this in MySQL? Thanks!

Answer 1

select zipcode, 
       avg(A00100) as average_income
from taxbyzip2008 
group by zipcode