Chapter 5- Sampling- Research

A group of elements selected from a larger population in the hope that studying the smaller group will reveal important things about the group that may represent the larger population.

Sampling is the process of selecting elements from which observations will be made. Sample is the group of people used for testing.

A list of all elements or other units containing the elements in the population.
*For example if you're going to survey all the students living in the dorms about the quality of food on campus but can only obtain a list of the rooms in the dorm.

Population selected for inclusion within a sampling frame. The primary sampling units are the dorm rooms that are selected in the first stage of sampling. The general student population becomes the secondary sampling unit.

Sampling in which everyone in the population has an equal chance of being randomly selected for the study and randomly assigned to either the experimental group or the comparison group.

1. Simple random sampling
2. Systematic random sampling
3. Stratified random sampling
4. Cluster sampling

A method for selecting a sample where every member does not necessarily have a greater than zero chance of being selected.

1. Convenience
2. purposive
3. Quota
4. Snowball sampling

Confident the researcher can be about the independent variable truly causing a change in the dependent variable.

1. Extraneous events
2. Passage of time
3. Testing effect
4. Instrumentation problems
5. Selection bias
6. Mortality of sample
7. Lack of casual direction

The extent to which a study's findings are applicable or relevant to a group outside the study
*it also includes the ability to be duplicated by other researchers, how the respondents of the measure were chosen, and the size of the sample.

Each person in the population is assigned a number, and then a sample is generated randomly from this population.
*Example would be drawing numbers from a hat.

So many numbers is selected randomly. Examples picking every hundredth person.

Method for obtaining a greater degree of representativeness.
*Example is dividing the total population into subgroups, then draw the sample from each stratum, using a probabilistic procedure.

The method of drawing a sample from a population in two or more stages..