Text Ch.8 Flashcards
Sampling links in with ______ validity
external
-the extent to which the findings drawn from the cases under examination may be used to make generalizations about phenomena outside the original study. Concerned with representativeness.
Sampling Error is the difference between ______ _______ and ______ ______
Population Parameter and Sample Statistic
Population Parameter Vs Sample Statistic
p. p= population characteristics, expressed in numeric terms when the responses of each member (or case) of the population are measured
s. s=
Population Parameter Vs Sample Statistic
p. p= population characteristics, expressed in numeric terms when the responses of each member (or case) of the population are measured
s. s=a subset of the p.p
3 factors in sample representativeness
- Sample Frame
-a list of the items or people forming a population from which a sample is taken.
Consider:
– Availability (or lack thereof)
– Completeness
– Accuracy - Sample Selection
- probability sampling
- non probability sampling - Sample size(if a probability sample)
- as sample size goes up, error goes down
Describe differences between probability and non probability sampling
Probability Sampling
- Based on probability theory
- Can estimate likelihood of representativeness
- Can estimate accuracy of sample statistics
- Appropriate for statistical analysis
types: • Simple random • Systematic selection • Stratified • Cluster
Non-Probability Sampling
-NOT based on probability theory
-CanNOTestimate likelihood of representativeness
-CanNOTestimate accuracy of sample statistics
-NOT appropriate for statistical analysis (including percentages/frequencies)
Types: Accidental and Purposeful(most typical)
Critiques of Sampling Frames: for probability sample and for Non-probability
Probability sample:
- What are possible gaps in the list?
- How could the sampling frame possibly introduce bias?
Non-probability sample:
- Convenience or purposive sample?
- Potential for ‘closed loops’?
.Does the goal of the research match the fact that it is non-probability or probability
Qualitative Research and NonprobabilitySampling
Words/text, rather than numbers
Deep description
Seeks transferable, dependable findings
Does not argue representativeness
Why use Non Probaility sampling
• Exploratory research
• Extremely small populations
• Unavailable/inadequate sampling frames
• High refusal populations
**Typically will stress that results may not be representative
Critiquing Sampling Size
Probability sample: . Homogeneity of population . Number of variables . Sample selection - Cluster sampling needs large sample sizes
Data Saturation
Data saturation: point at which data collection no longer provides the researcher with new information
Non Probability sampling: how to choose sampling size
Focus on quality of information obtained, rather than quantity of cases
Data saturation: point at which data collection no longer provides the researcher with new information
population
in research the group that a researcher wishes to generalize about(ex: Canadian citizens); in content analysis, the texts most appropriate for answering the research questions
sampling
the process of drawing a sample of cases from a larger population
First step in a research project is to clearly identify the population being studied: 3 factors
- Unit of analysis(indv,political parties,etc)
- Geographic location
- Reference perios