Chapt 5 census: studying the entire population of interest cross-population generalizability: findings from one popular in one country to one population in another country. The distribution of characteristics among the elements of a representative sample is the same as the distribution of those characteristics among the total population. In an unrepresentative sample, some characteristics are overrepresented or underrepresented. Random selection of elements maximizes sample representativeness sampling error: the difference between the characteristics of a sample and the characteristics of the population from which it was selected. Random sampling error may or may not result in an unrepresentative sample. The magnitude of sampling error due to chance factors can be estimated statistically sample statistic: the statistic computed from sample data (i. e mean) is identical to the population parameter: the statistic computed for the entire population. The value at the peak of the bell curve represents the norm for the entire population.