Earmarks and the house that approves them…
Posted August 23rd, 2009 by SpicyJust found a new data set that I couldn’t help running some stats on. OpenSecrets.org published this table which lists all of the members of the house, the number of earmarks they requested, and the total dollar amounts.
The columns of the data are:
- Representative Name
- State
- Number of Earmarks
- Total Cost
- Solo Earmarks
- Solo Cost
The solo columns are for earmarks where that representative was the only representative who requested the earmark.
Republicans vs. Democrats
The first obvious division is to split the data on party lines and see if their behavior is any different.
| Column | Mean Democrats | Mean Republicans | P-value | Histogram |
|---|---|---|---|---|
| Total Earmarks | 26.8 | 22.3 | 3.26E-4 |  |
| Total Cost | $37,402,953 | $30,683,681 | 0.02873 |  |
| Solo Earmarks | 10.3 | 9.2 | 0.0925 |  |
| Solo Cost | $7,606,210 | $7,746,574 | 0.7782 |  |
Red: Republicans, Blue: Democrats. Significant p-values are in bold.
Table 1. The above table shows that the average number of earmarks that are approved is significantly higher for democrats than for republicans and also that democrats get significantly more money for their earmarks than republicans do. Please note that when I say “significantly” I mean it in a statistical sense. The p-values (or the probability that the difference between democrats and republicans is purely by chance) for the first two rows of the table are signifiant ( less than 0.05). You can interpret this as having a less than 5% chance of this occurring completely by chance. However, when looking at solo earmarks there is not a significant difference in the number of earmarks granted or their cost.
For the Statisticians: To calculate the p-value I used the wilcoxon rank sum test as the distributions are not normally distributed.
However, I feel obligated to point out that because the house has a majority of democrats (237 to 163) it may be easier for democrats to get their earmarks passed, thus there are more for democrats. For comparison, data from when the GOP has control of the house is required.
2 Responses to “Earmarks and the house that approves them…”
August 29th, 2009 at 3:25 pm
Interesting! Can’t you do some sort of controlling for the # of dems vs #of reps ?
August 29th, 2009 at 3:49 pm
Actually, you don’t have to. When you are testing if the means are different from two populations all you are really looking at are the mean and standard deviation (in a t-test at least). So the sizes don’t have to be equal to test this.
The problem is one of confounders. I don’t have an estimate for how much easier it may be to get earmarks passed for dems vs reps due to the dems controlling the house. So there may be a bias that we would need to estimate, which we could, if we had this data from when the reps controlled the house.
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