where ray is Pearsons correlation coefficient for a and y Just Pearson's correlation This "test of trend"is nothing more than Pearsons correlation coefficient. Let' s try this list Iy a weight 1.|0 2.|02 3.|03 4.|11 21 corry a [fw=weight] (obs=14) y a 1.0000 0.17771.0000 return listwhere ray is Pearson’s correlation coefficient for a and y. Just Pearson’s correlation This “test of trend” is nothing more than Pearson’s correlation coefficient. Let’s try this. . list +----------------+ | y a weight | |----------------| 1. | 0 1 19 | 2. | 0 2 31 | 3. | 0 3 67 | 4. | 1 1 1 | 5. | 1 2 5 | |----------------| 6. | 1 3 21 | +----------------+ . corr y a [fw=weight] (obs=144) | y a -------------+------------------ y | 1.0000 a | 0.1777 1.0000 . return list