True vs Simple Population Density?

Question

What is the difference between true population density and simple population density?

Answer 1

do you mean "sample population?"  If not, I don't know.

  If so then,  statistically speaking we never get the true mean of a population if the population is large.  For instance, what is the mean height of the people of the United States at any given time?  What we do is take samples of the population.  If we are careful about how we take the samples then we will include the natural variation of the population in a reasonable way.  But our sample, no matter how good it is will always have error because we do not have all the information.  In order to have all the information we would have to measure the heights of 330 million people.  This is impractical under most circumstances so we satisfy ourselves with a carefully derived sample.