Sampling Flashcards
(13 cards)
What is sampling
Sampling is the process of selecting a group of individuals from a larger population to study.
What is Probability Sampling
Each member of the population has a known and equal chance of being selected into the sample.
What is Non-Probability Sampling
The probability of each member of the population being included in the sample is unknown
What are the key components of a sample
- Sample Element: The unit being studied
- Population: Specified grouping of study elements
- Sampling Frame: List of all elements in the population
- Population Parameter: A value for a given variable in a population
- Sample Statistic: A value of a given variable in the sample
What are the probability Sampling methods
- Simple random
- Systematic random
- Stratified random
- Cluster random
SIMPLE RANDOM SAMPLING
Definition: Every individual in the population has an equal chance of being selected.
How It Works:
Create a complete list of the population
Assign numbers to each individual.
Use a random generator (e.g., lottery method, computer software) to select participants.
SYSTEMATIC RANDOM SAMPLING
Definition: Every k-th individual is selected after a random starting point
How It Works: List all members of the population.
Choose a random starting point
Select every k-th individual (e.g., every 5th person).
STRATIFIED RANDOM SAMPLING
Definition: The population is divided into subgroups (strata), and individuals are randomly selected from each stratum.
How It Works: Divide the population into groups based on a shared characteristic (e.g., age, gender, income).
Randomly select individuals from each group.
CLUSTER RANDOM SAMPLING
definition: The population is divided into clusters (groups), and entire clusters are randomly selected.
Divide the population into natural groups (e.g., schools, neighborhoods).
Randomly select entire clusters instead of individuals.
Study everyone within the selected clusters.
PURPOSIVE SAMPLING
Sample selection based on prior knowledge of subject or population
Based on particular characteristics/attributes
‘CONVENIENCE’ SAMPLING
Participants are selected based on availability and willingness to participate.
Can be low cost and easy to access
QUOTA SAMPLING
The researcher sets quotas for certain groups and selects participants non-randomly until the quotas are met.
SNOWBALL SAMPLING
Identify 1+ participants who meet the eligibility requirements
Rely on these participants to identify and refer others to participate
