Question 1

Is a bigger sample always more representative?

Accepted Answer

Not necessarily. While a larger sample size can increase statistical confidence, representativeness is more important. A very large but biased sample (e.g., 10,000 people all from one city) is far less useful than a smaller, well-chosen sample of 500 that accurately reflects the entire population's demographic and geographic mix. The method of selection is often more critical than the sample size alone.

Question 2

Why would a business ever use non-probability sampling if it's more biased?

Accepted Answer

Businesses often face constraints of time and money. Non-probability methods like convenience or quota sampling are significantly cheaper, faster, and easier to implement than probability methods. For initial exploratory research, testing a concept, or when a high degree of statistical accuracy is not the primary goal, the speed and low cost can be a justifiable trade-off against the higher risk of bias.

Question 3

What is the difference between stratified sampling and quota sampling?

Accepted Answer

Both methods involve dividing the population into subgroups. The key difference is how participants are selected from these subgroups. In stratified sampling (a probability method), participants are chosen randomly from each subgroup. In quota sampling (a non-probability method), the researcher selects participants non-randomly until a pre-set quota for each subgroup is filled, often based on convenience. This makes stratified sampling more statistically robust but also more complex and expensive.

Sampling

What you need to know

Sampling