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Transportation Spending by Low-Income California Households ...

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expenditures to the poverty threshold, and we calculated the 11th and<br />

27th percentiles of that distribution, which were 1.15168 and 1.75536,<br />

respectively. We classified households with an expenditure-to-povertythreshold<br />

ratio less than 1.15168 as poor, those with a ratio below<br />

1.75536 as low-income, and those with a ratio at or above 1.75536 as<br />

higher-income.<br />

Appendix C contains a sensitivity analysis that demonstrates how the<br />

results change under several different treatments of the data.<br />

Sample Sizes for the Datasets<br />

The following table summarizes the information on sample sizes for<br />

the datasets:<br />

<strong>Low</strong>-<br />

<strong>Income</strong><br />

Higher-<br />

<strong>Income</strong><br />

Poor<br />

Total<br />

PUMS Bay Area<br />

<strong>Households</strong> 8,850 22,267 98,845 121,112<br />

Persons 26,314 64,474 259,665 324,139<br />

BATSa<br />

<strong>Households</strong> 275 742 12,449 13,191<br />

Persons 533 1,816 28,626 30,442<br />

CES metropolitan <strong>California</strong><br />

Consumer Units 1,215 2,984 8,069 11,053<br />

CES metropolitan <strong>California</strong><br />

vehicle users 561 1,867 7,170 9,037<br />

CES metropolitan <strong>California</strong><br />

vehicle purchasers 40 127 605 732<br />

CES metropolitan <strong>California</strong><br />

transit users 237 466 628 1,331<br />

aBATS income data are missing for 1,873 households and 3,917 persons. Of<br />

those households with incomplete income data, 919 households reported that their<br />

income was $40,000 or higher, 153 reported that their income was below $40,000,<br />

and 801 were missing all income data. We did not include these incomplete income<br />

reporters in our analyses.<br />

Weights<br />

Sample weights are used with each of the datasets to make the data<br />

representative of the desired entity. In CES and PUMS data, the weights<br />

are designed to represent the entire United States, rather than <strong>California</strong><br />

137

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