Cluster sampling - sampling population is i) ii) divided into groups clusters elements within each cluster are selected. cluster 1 all provinces or territories. Non-random (non-probabil i ty) sampl i ng designs. does not follow the theory of probability! number of elements either unknown or cannot be individually identified. consent to participate not based on an obvious or visible characteristic common among market research and media. Application - construction of a historical reality or description of a phenomenon. No need for information on sampling frame, sample elements, location characteristics of both random and non-random sampling designs. the greater the heterogeneity or diversity, the greater the number of respondents needed. 1: degree of accuracy level of variation. Objective: to estimate the age of students in this lecture hall: assume willing to tolerate an error of 0. 5 years, confidence level 95, assume standard deviation is within 2 years.