5. The following table shows the unemployment rates for Blacks in Miami and in four comparison cities before and after the Mariel boatlift in 1980 as well as the Mariel boatlift that did not happen in 1994. Unemployment rates for Blacks Miami Atlanta Houston Los Angeles Tampa-St. Petersburg Before (1980) 8.3 11.7 8.9 7.9 12.7 After (1980) 9.6 14.3 12.4 9.1 14.6 Before (1994) 10.1 11.4 10.8 9.2 14.6 After (1994) 13.7 5.2 14.6 10.4 5.0 b) Calculate the difference-in-difference estimate for the effect of 1994 Mariel boatlift that did not happen on unemployment rate. Does the difference-in-difference estimate represent the causal effect? Explain why or why noy