Definition
The Income Rank Score rank orders individuals based on their estimated income level. Individuals with a higher score are more likely to have a higher income.
Technical Details
The model was built from multiple surveys where respondents indicated their household income level from a set of income ranges. These income ranges were then mapped to their midpoint, which served as the target variable for training a regression model. For example, “Between $20,000 and $35,000” was mapped to $27,500.
The Income Rank Score was trained on about 18,000 survey responses collected by Murmuration from 2021 - 2023. The surveys used stratified random sampling to ensure national representativeness across age, race, gender, partisanship, education and geography.
The regression model was trained using gradient-boosted decision trees and then transformed to a percentile rank. Model features were drawn from the Atlas by Murmuration dataset, which includes demographic (age, race, gender, etc.), commercial, geographic, and vote history information for all registered voters nationally.
Scores range from 0-100, where higher scores indicate greater likelihood that a voter has a higher income. The score represents the model's predicted percentile of a given voter’s household income. For example, if a voter has a score of 85, the model predicts that this voter has a higher income than 85% of voters.
We validated the model's accuracy using a held-out set of 3,669 polling respondents (20% of the original survey sample) whose data was not used during model development. Individuals in the top 20% of the Income Rank Score had an actual average income of $128,000, compared to $44,000 for those in the bottom 20%, indicating that the score reliably distinguishes between higher and lower income voters.
Use Cases
The Income Rank Score can be used in a variety of ways when building a campaign strategy and planning voter engagement. It can also be used independently or in conjunction with other scores. Below are a few examples for how partners could use this score:
- Demographic Targeting: Partners can use the Income Rank Score to identify and target voters by estimated income level. By filtering to individuals with high or low scores, partners can tailor outreach to constituencies whose economic circumstances make them more receptive to specific economic messages or policy priorities.
- Fundraising and Donor Targeting Partners can use the Income Rank Score to prioritize outreach to higher-propensity donors by focusing solicitation efforts on individuals estimated to have greater financial capacity. This helps campaigns allocate fundraising resources more efficiently and personalize ask amounts to better reflect a voter's likely giving range.
Targeting Table
The table below shows the score values associated with each decile to help you more easily target using the Income Rank Score nationally. The Income Rank Score is percentile scaled nationally, meaning scores are distributed evenly across the full voter file: 10% of voters score between 90–100, 10% between 80–90, and so on. Note however that these score cutoffs may be different in your local districts.
| To target the top... | Set the minimum score value as... |
| 10% | 90 |
| 20% | 80 |
| 30% | 70 |
| 40% | 60 |
| 50% | 50 |
| 60% | 40 |
| 70% | 30 |
| 80% | 20 |
| 90% | 10 |
| 100% | 0 |