Sampling and Theory Flashcards

6327592313	What is sampling?	A sample is a subset taken from the target population (population of interest)	0
6327687741	population	The population shares common characteristics that you, the researcher, define before your study begins.	1
6327695511	target population	Target population is the group from which you can select a sample (from the population you have defined)	2
6327786747	Sampling Plan	How you put it all together and follow through with design - Qualitative, Quantitative?	3
6327704845	Quantitative Sampling (usually probability)	• Sample determines external validity (can you generalize your findings from the sample to the population (hopefully) • And to some extent, internal validity (can you rule out all other alternative explanations for the results	4
6327719955	Steps in Sampling	• Define the population • Develop a plan - how you will select a sample • Determine the size • Select the sample • Compare if the sample truly represents the characteristics of the population.	5
6327888553	power analysis	used to calculate the minimum sample size required so that one can be reasonably likely to detect an effect of a given size	6
6327730378	Probability Sampling (usually for quantitative)	• Everyone has an equal chance of being selected • Random - one step do it all • Systematic - select from pre-set intervals • Stratified -fixed % randomly drawn from pre-divided subgroups • Cluster - randomly, sequentially drawn from already existing larger subgroups	7
6327742451	Examples of Clustering	• Random - assign each individual a number and choose the numbers from a pile of numbers. • Systematic - assign each individual a number and choose odd numbers • Stratified - Determine % of patients that are male or female and choose those % in your sample	8
6327754381	Non-Probability Sampling (usually for qualitative)	• Do not know the parameters of the population therefore use non-random methods of selection • Convenience-what is available • Purposive-particular characteristics that fit your criteria but non-random • Snowball- word of mouth networking • Quota- set number of subgroups according to the population characteristics but non-randomly	9
6327761960	Relation of Sampling to Validity	• External validity means that you can accurately generalize the findings from your sample the population. • If the selection of the participants is biased then the results of the study cannot be generalized to a larger population. • Selective effects (error in sampling and selection) is a threat to external validity.	10
6327768835	Qualitative Sampling (usually non-probability)	• Is purposive - choose those who can offer the most relevant information about your topic • Typically, establish criteria or what you want to include then find participants who fit the bill	11
6327776950	Boundary Setting	Can choose a sample and further bound the study by choosing: setting, stories, groups, images, experiences, concepts, objects	12
6327818978	Sampling - Qualitative Characteristics	• Typical- the majority • Extreme or deviant- most extreme to compare to the majority • Comprehensive/Maximum Variation-all the participants or cases that match the criteria are included • Confirming or Disconfirming • Reputational- recommended by experts • Comparable- select cases with the same characteristics that match the criteria over a period of time. • Convenience- can be included most quickly or conveniently	13
6327820886	Sampling size, what is reasonable?	Quantitative - large size, minimum 30 per variable, but do POWER analysis to confirm sample is large enough Qualitative - small size, 3-5, or single subject	14
6328056026	Saturation	qualitative - you've interviewed so many people that you start to get no new info	15
6327842676	Why is theory important in quantitative research?	Guides your decisions: problem statement, which variables to measure, setting boundaries, data collection, analysis, But HELPS TO SEE THE BIG PICTURE	16
6327846538	Why is theory important in qualitative research?	develop a theory, interpret data	17
6327874987	what is theory?	• Inter-related concepts (observation), constructs (surmised, categories), relationships, propositions (statements that govern the relationships, suggestions) that can explain or predict human experience - and make it orderly. • Deductive- verify or refute • Inductive- explain, develop	18