I learnt that for random sample, we can use sample size calculator for estimations, and power and sample size program for hypothesis testing. What about cluster sampling? How do we measure the sample size?
In terms of cluster sampling, the following may help answer your question:
In some situations, cluster analysis is only appropriate when the clusters are approximately the same size. This can be achieved by combining clusters. If this is not possible, probability proportionate to size sampling is used. In this method, the probability of selecting any cluster varies with the size of the cluster, giving larger clusters a greater probability of selection and smaller clusters a lower probability. However, if clusters are selected with probability proportionate to size, the same number of interviews should be carried out in each sampled cluster so that each unit sampled has the same probability of selection.
From https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Cluster_sampling.html
In terms of cluster sampling, the following may help answer your question:
In some situations, cluster analysis is only appropriate when the clusters are approximately the same size. This can be achieved by combining clusters. If this is not possible, probability proportionate to size sampling is used. In this method, the probability of selecting any cluster varies with the size of the cluster, giving larger clusters a greater probability of selection and smaller clusters a lower probability. However, if clusters are selected with probability proportionate to size, the same number of interviews should be carried out in each sampled cluster so that each unit sampled has the same probability of selection.
From https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Cluster_sampling.html
Fatimah, let me add some information about cluster sampling. From what I know, one uses it when the whole population in the area of concern is not known. So one divides the area into a number of clusters distinguished by certain features. From a "population" of clusters, a sample size is computed and randomly selected. The whole sub-populations in the clusters selected shall be the participants in the research. Ed
Determining the sample sizes involve resource and statistical issues. Usually, researchers regard 100 participants as the minimum sample size when the population is large. However, In most studies the sample size is determined effectively by two factors: (1) the nature of data analysis proposed and (2) estimated response rate.
For example, if you plan to use a linear regression a sample size of 50+ 8K is required, where K is the number of predictors. Some researchers believes it is desirable to have at least 10 respondents for each item being tested in a factor analysis, Further, up to 300 responses is not unusual for Likert scale development according to other researchers.
Another method of calculating the required sample size is using the Power and Sample size program (www.power-analysis.com).