Sampling for Research

Types of Research Quantitative – the collection & analysis of data to describe, explain, predict, or control phenomena of interest Qualitative – the collection, analysis, & interpretation of comprehensive narrative and visual data to gain insights into particular phenomenon of interest Mixed-Methods

Samples for Quantitative Studies Generalizability – Sample chosen should be representative of the population being examined Sample Size – The larger the population, the smaller %age required to get a representative sample 50% for a sample of 500, 20% for a sample of 1,500 – For smaller populations (n=100 or fewer), the entire population is typically sampled.

Samples for Quantitative Studies

Sample Error – A random, unknown characteristic of the sample – causes the sample to not be as representative as 1 st thought Sample Bias – A systematic sampling error – Typically caused by the researcher

Samples for Quantitative Studies Methods of Sampling: Simple Random Sample - every member of the population has an equal chance of being selected

Samples for Quantitative Studies Methods of Sampling: Stratified Sample - Population is divided into groups. Then a random sample is taken from each group

Samples for Quantitative Studies Methods of Sampling: Cluster Sample - Population is divided into groups. Then an entire group is randomly chosen with all members of the randomly chosen group used in the sample

Non-Random Sampling Methods Non-Random Methods of Sampling: Convenience Sample - A sample of well...convenience. Not scientific, just easy. Conclusions about the population cannot be drawn from this type of sample. Purposive Sample Judgment sampling The process of selecting a sample that is believed to be representative of a given population. Quota Sample – Process of selecting a sample based on required, exact numbers (quotas) of individuals or groups with varying characteristics.