Given that about 20 percent of stars are sun-like, the researchers say, that amounts to several tens of billions of potentially habitable, Earth-size planets in theMilky WayGalaxy. “When you look up at the tho
Get a random sample of the population. If your sample is not random, estimates of the proportion (and other quantities) may be biased. For example, if you want to estimate the proportion of boys in an elementary school, you could assign a number to each student, then randomly pick a sam...