Theory Chapter 4 Flashcards
What is census?
It is the process of examining every member in a population.
What is a sample?
It is a subset of the population that is representative of the entire population.
What is research error?
There are two research errors:
- Sampling error - error related to selecting a sample from a population
- Non sampling error - error created by every other aspect of a research study
What is measurement error?
It is divided into 2:
- Random error - problems where measurements and analysis vary inconsistently from one study to another which are caused by unknown and unpredictable variables.
- Systematic error - produces incorrect/invalid results in the same direction or same context.
Describe Probability and non probability sampling.
Probability uses mathematical guidelines where each unit’s chance for selection is known and allows researchers to calculate the amount of sampling errors. Non probability does not follow the mathematical guidelines so therefore does not calculate.
Name the issues of probability and non probability sampling.
- Purpose if study
- Costs vs value
- Time constraints
- Amount of acceptable errors
Explain Unqualified volunteer sample.
Researchers have no control over the respondents who participate in a research study. They are haphazard and produce results that are invalid or unreliable.
Explain Qualified Volunteer sample.
Is selected by using probability sampling and employs controls to limit the type of person to participate in the project.
Available sample (convenience sample)
Collection of readily accessible subjects, elements or events for study. It is helpful in providing explanatory information and produce useful data, the samples are a bit problematic because it contains known quantities of errors
Purpose sampling
Includes respondents, subjects or elements selected for specific characteristics or qualities and eliminates those who fail to meet these criteria.
Quota sample
Subjects are selected to meet predetermined or known percentage
Snowball sample
The researcher randomly contacts a few qualified respondents and ask them for the names of friends, relatives etc who may also qualify for the research which then are contacted to determine if they qualify for the research. Sample may be contaminated by bias.
Simple Random sample
Each subject element, event or unit in a population has an equal chance of being selected.
Random Digit Dialing or RDD
Randomly selecting phone numbers
Address-based sampling or ABS
Selection of random households to participate in a survey.
