3 - Population and Samples Flashcards
(25 cards)
What is a population in statistics?
The entire set of individuals or items that you’re interested in studying.
What is a sample?
A subset of a population used to estimate characteristics of the whole population.
What is a parameter?
numerical value that describes a population (e.g. mean or standard deviation).
What is a statistic?
A value calculated from a sample that estimates a parameter.
What is the difference between qualitative and quantitative data?
Qualitative is non-numerical (e.g., eye color), while quantitative is numerical (e.g., height).
What is the difference between discrete and continuous data?
Discrete is counted (specific values); continuous is measured (any value in a range).
What is the difference between primary and secondary data?
Primary data is collected firsthand; secondary data is collected by someone else.
Define sampling frame.
A list of all sampling units in the population.
What is a sampling unit?
An individual item or person from the population.
What is a census?
A survey that includes every member of the population.
How is a simple random sample taken?
Using a sampling frame and random numbers or lottery method to select units.
What is an unrestricted random sample?
Similar to simple random sampling but allows repeats (sampling with replacement).
What is systematic sampling?
Selects every (x )th item from a list, after a random starting point.
How is the sampling interval in systematic sampling calculated?
Divide population size by sample size
What is proportional stratified sampling?
Divide population into strata, then sample from each based on proportion
What is disproportional stratified sampling?
Sampling from strata without considering their proportion in the population.
What is cluster sampling?
Randomly select whole groups (clusters) from the population for the sample.
What is judgmental sampling?
Selects samples based on the researcher’s judgment.
What is snowball sampling?
Existing sample members recruit future participants.
Give one advantage of using a sample over a census.
Quicker and less expensive.
Give one disadvantage of sampling.
May not be fully representative of the population.
One advantage of simple random sampling?
minimizes selection bias.
One disadvantage of stratified sampling?
Requires detailed population information to divide into strata.
Advantage of systematic sampling?
Simple and quick to use.
