Chapter 1 : Data Collection Flashcards
(20 cards)
Population
The entire set of items (sampling units) in the group being studied
Census
Measuring every member of a population
Sampling frame
list of sampling units
What are the +ve and -ve of taking a census?
+ Accurate
- Expensive / Some testing destroys item (battery life)
What are the three main random sampling methods?
Simple Random Sampling
Systematic Sampling
Stratified Sampling
What are the two Non-random sampling methods?
Opportunity sampling
Quote Sampling
Simple random sampling
equal chance of being selected, use random number
generator alongside sampling frame
+ve and -ve of simple random sampling
+ bias free
- sampling frame required
Systematic sampling
Takes every kth unit, pick random number between 1 and k for start point
+ve and -ve of systematic sampling
+ quick to use
- sampling frame required
Stratified sampling
proportionally represents strata (groups) in the sample to
reflect the population, use either simple random or systematic to fill the groups
+ve and -ve of stratified sampling
+ reflects population
- need clear strata for population
+ve and -ve of opportunity sampling
+ easy, cheap
- unlikely to be representative
Opportunity sampling
Sample based on who/what is available
Quota sampling
starts with quotas to be filled, but not necessarily
representative of the population. Groups filled using opportunity sampling
+ve and -ve of quota sampling
+ no sampling frame needed
- not random, potential bias
Qualitative data
Non-numerical data
Quantitative data
Numerical data
Discrete data
Can only take certain values
Continuous data
Can take any calue in a range
