APA Dictionary of Psychology

n. in statistics, the process of approximating a population parameter from sample data while allowing for some degree of uncertainty by giving a range of values within which the parameter will most likely fall. Estimation usually requires a large random sample, from which one can calculate point estimate values, such as the mean and standard deviation, in the larger population of interest. The process of estimation also involves building a confidence interval around the obtained sample value, plus and minus some margin of error.