Correspondence: 117

RACIAL DUALISM IN ST. LOUIS

BY Bennett Harrison

In his article entitled: "Racial Economic Dualism in St. Louis, ''1 David Streifford reports on my recent lrmding for St. Louis that black unemployment and earnings did not differ significantly be- tween the central city and the rest o f the SMSA, whereas the rates for whites were indeed spatially sensitive. 2 He also cites Benjamin Cohen's wo)k on the cyclical component of central city suburban job changes over time, and Cohen's argument that black unemployment is spatially insensitive, a Using 1970 Census of Population data, Streifford reports that he has found very different results for St. Louis; county-wide Blacks do show lower unemployment rates and higher average earnings than central city Blacks.

Like so many writers on the subject of racial and/or spatial varia- tions in economic indicators, Streifford has failed to account for sampling v~tdation in reporting his statistics. The unemployment and earnings data are drawn from very small samples. The Census (or other govenarnent agency) documents in which these data are pre- sented almost always provide order-of-magnitude estimates of the sampling error, with which to construct confidence intervals around various test statistics. The more an analyst (or his readers) cares about the social/political consequences o f an economic analysis, the more important it is to observe good methodological practice and use these second order statistics.

I have not checked the Census volume cited by Streifford to test whether the city-suburban black wage differentials that he reports are in fact statistically significant. I have checked another data source on the unemployment differentials, however. According to the Bureau of Labor Statistics, in 1971, a 90% confidence interval on the black St. Louis SMSA unemployment rate was 7.9-11.7%. The cor- responding central city interval was 6.8-11.2%. 4 Naturally, an even higher significance level (say, odds of 95 out of 100) would produce even broader intervals. In other words, there is no statistically signifi- cant evidence that the situation (at least with respect to unem- ployment) was any different in St. Louis in 1971 than in 1966, when I took my measurements. Substantively, Blacks are discriminated against (or otherwise excluded from full economic participation) re- gardless of where in the St. Louis area they happen to live.

118 The Review of Black Political Economy

I have written this note to encourage analysts - especially analysts o f such politically "ho t " material as that discussed in the Streifford paper - to be as careful as poss~le in adhering to good scientific procedures. Those o f us who advocate radical social change cannot afford to have our work sidetracked by often gratuitous - if tech- nically correct - criticisms of our methodological approach. Some- times, there is no choice but to use point estimates (although in such cases, the reader should be warned). Where interval estimates can be constructed (in fact, I try to report entire income distrl"butions where possible!), they should almost always be used.

1Rev. Black PoL Econ., Spring 1974.

2Bennett Harrison, "Education and Underemployment in the Urban Ghetto,"Amer. Econ. Rev., Dec. 1972; Harrison, Education, Training, and the Urban Ghetto (Baltimore: Johns Hopkins, 1972); and Harrison, Urban Economic Development (Washington D.C.: The Urban Institute, 1974).

3Benjamin Cohen, "Trends in Negro Employment Within Large Metropolitan Areas," Public Policy, Fall 1971.

4Bureau of Labor Statistics, U.S. Dep~ of Labor, Geographic Profile of Employment and Underemployment, Report No. 402, Govt. Prntg. Off., 1972, table 6.