Appendix 2a.

Individual-level correlations between illiteracy and race/nativity by US states based on 1930 US Census data

^aJim Crow states are shaded in light grey.

^bThese coefficients were calculated using cross tabulation based on ‘native and foreign-born whites’/'negro’ and literate/illiterate, similar to what Robinson reported in his paper.

^cAll correlations were statistically significant at p < 0.0001.

^dThe phi coefficient is a measure of the degree of association between two binary variables. This measure is similar to the correlation coefficient in its interpretation. Two binary variables are considered positively associated if most of the data falls along the diagonal cells. In contrast, two binary variables are considered negatively associated if most of the data falls off the diagonal. The phi coefficients and p-values were calculated using VassarStats calculator: http://faculty.vassar.edu/lowry/VassarStats.html (Accessed on 10 June 2008).

^eThese coefficients were calculated using cross tabulation based on ‘native whites’/'negro’ and literate/illiterate.

^fThe expected frequency of one of the cells was <5, thus the Pearson Chi-square was not calculated.