In previous case, it was said that joint probability is zero for Set whose area is zero. In this lecture (6:26) while calculating Marginal PMF (which is over a curve, not an area), how come probability is non-zero?
Joint PDF is in two or more dimensions, but marginal PDF is just for 1 dimension because we only calculate it for one variable at a time. there is no concept of area in one dimension whatsoever. It's just a plain old PDF which is probability along a unit length.
In previous case, it was said that joint probability is zero for Set whose area is zero. In this lecture (6:26) while calculating Marginal PMF (which is over a curve, not an area), how come probability is non-zero?
it is actually the integral over a "length" (interval) but it somehow shows like a curve in the video.
Joint PDF is in two or more dimensions, but marginal PDF is just for 1 dimension because we only calculate it for one variable at a time. there is no concept of area in one dimension whatsoever. It's just a plain old PDF which is probability along a unit length.