If N = 10 and the rank order correlation coefficient (ρ) is 0.80, then what is the value of ∑d2?

Data from twelve European countries shows the correlation coefficient (r) between car ownership levels and road deaths is 0.73. Which statement correctly interprets this statistic?

Which correlation coefficient method is specifically used when both continuous variables have been artificially reduced to dichotomous variables (naturally continuous but converted to dichotomy)?