Chapter 5, 8, 9 & 4 Flashcards
Social Research - Approaches and Fundamentals
Purpose of research
Collecting info reagrding target population
Steps for sampling
- Defining target population
- Obtaining sampling frame
- Deciding sampling design
Coverage error
Differences between the target population and the sampling frame, when the sampling frame does not include all members of the population. Ex. telephone interview omits people without a phone
Two types of coverage error
- Undercoverage: Belong to the population, but are not represented in the sampling frame (most problematic!!)
- Overcoverage: are not part of the target population, but are listed in the sampling frame
Sampling designs
Part of research plan that indicates how cases are being selected for observation
Sampling designs divided in 2 classes
- Probability sampling (4 ways): all cases are randomly selected
- Non probibility sampling: cases are non-randomly selected
Random selection
Each element in a set has an equal chance of being selected. If not, it is called biased
Simple random sample
Equal chance in random selection
Sampling error/random error
Differences between a population characteristic (parameter) and the sampling estimate (statistic) of that characteristic
Systematic error
Simple random sample only leads to representative info when the coverage error is small, if not, it is called systematic error
Confidence interval
Tells us that interval estimates obtained with the procedure are likely to contain the population parameter 95% of the time
Stratified random sampling
Stratification of sampling frame in group of elements that share the same characteristics (strata). Guarentees that even smaller strata will be represented in sample
Disproportionate stratified random sampling
Variation of random sample. Unequal chance of selection depending on how large stratum is
Cluster sampling
The population is broken down into groups of cases, called clusters
Two ways to sample
- Single staged cluster sampling –> sampling with cluster level. Primary sampling units.
- Multistage cluster sampling (nested sampling). Secondary sampling units.
Systematic selection
Consists of selecting every case from a complete list or file of the population, starting with a randomly chosen case from the first K cases on the list. 2 Requirements (Sampling interval & a random start)
Sampling interval
The ratio of number of cases in the population to the desires sample size
A random start
Refers to the process of randomly selection of the initial case between 1 and K.
Characteristics of survey research
- Large scale probability sampling
- Pre-constructed questionnaire/interview protocol
- Coded answers & statistical analysis
Descriptive surveys
Describe the distribution within a population of certain characteristics attitudes or experiences
Explanatory surveys
Beyond description to investigate relationship between two or more variables and attempts to explain these
Research design
Overall structure of a study