questions and answers 2025\2026 A+ Grade
Population
- correct answer The whole set of terms that are of interest.
Census
- correct answer Observes or measures every member of a population
Sample
- correct answer A selection of observations taken from a subset of the population which is used to find
information about the population as a whole
Census advantages
- correct answer It should give a completely accurate result
Census disadvantages
- correct answer - Time consuming and expensive
- Cannot be used when the testing process destroys the item
- Hard to process large quantity of data
Sample advantages
- correct answer - Less time consuming and expensive than a census
- Fewer people have to respond
- Less data to process that a census
Sample disadvantages
- correct answer - The data may not be as accurate
- The sample may not be large enough to give information about small sub-groups of the population
,Sampling units
- correct answer Individual units of a population
Sampling frame
- correct answer Individually named or numbered to form a list called a sampling frame
The sample should be
- correct answer representative of the population
Random sampling helps to remove
- correct answer bias from a sample
Random sampling methods
- correct answer - Simple random sampling
- Systematic sampling
- Stratified sampling
Simple Random Sampling
- correct answer A simple random sample of size n is one where every sample of size n has an equal
chance of being selected
Systematic sampling
- correct answer The required elements are chosen at regular intervals from an ordered list
Stratified sampling
- correct answer The population is divided into mutually exclusive strata (which are proportional to the
population) and a random sample is taken from each.
Stratified sampling equation
- correct answer The number sampled in a stratum = (number in stratum/number in population) x
overall sample size
, Simple random sampling advantages
- correct answer - Free of bias
- Easy and cheap to implement for small populations and small samples
- Each sampling unit has a known and equal chance of selection
Simple random sampling disadvantages
- correct answer - Not suitable when the population size or the sample size is large
- A sampling frame is needed
Systematic sampling advantages
- correct answer -simple and quick
-suitable for large samples and populations
Systematic sampling disadvantages
- correct answer - A sampling frame is needed
- It can introduce bias if the sampling frame is not random
Stratified sampling advantages
- correct answer - Sample accurately reflects the population structure
- Guarantees proportional representation of groups within a population
Stratified sampling disadvantages
- correct answer - Population must be clearly classified into distinct strata
- Selection within each stratum suffers from the same disadvantages as simple random sampling
Non-random sampling methods
- correct answer - Quota sampling
- Opportunity (convenience) sampling
Quota sampling
- correct answer An interviewer or researcher selects a sample that reflects the characteristics of the
whole population