3.2 Market Research – Sampling
Why We Need Sampling 📊
Imagine you’re a chef trying to decide which flavour of ice‑cream will be most popular in a town of 10,000 people. Tasting every single scoop from every household would take forever and cost a fortune. Sampling lets you taste a few scoops, guess the flavour that most people like, and make a decision quickly. In business, sampling lets researchers gather useful information without having to survey every single customer or potential buyer.
Key benefits:
- Cost‑effective – less money for questionnaires, interviews, or lab tests.
- Time‑saving – data can be collected in days or weeks instead of months.
- Manageable – easier to analyse and interpret a smaller dataset.
Limitations of Sampling ⚖️
While sampling is handy, it’s not perfect. Think of it like guessing the colour of a hidden marble in a jar. Even if you pick many marbles, you might still miss the rare colour. In research, this is called sampling error.
- Sampling Bias: If the sample isn’t truly random, the results may favour certain groups. Example: surveying only people in a shopping mall might miss older adults who shop online.
- Non‑response: Some people may refuse to answer or drop out, skewing the data.
- Small Sample Size: A tiny sample can lead to large variability. The smaller the sample, the higher the chance that the results are just a fluke.
- Cost vs. Accuracy Trade‑off: Bigger samples improve accuracy but cost more, so researchers must balance budget and precision.
Remember: Sampling gives an estimate, not an exact answer. The goal is to make the estimate as close to the truth as possible while staying within budget and time limits.
Sample Size Formula (Quick Math) 📐
For a simple random sample, the required size can be approximated by:
\$n = \frac{Z^2 \, p \, (1-p)}{E^2}\$
where:
- \$Z\$ = Z‑score (e.g., 1.96 for 95% confidence)
- \$p\$ = estimated proportion (use 0.5 for maximum variability)
- \$E\$ = desired margin of error (e.g., 0.05 for ±5%)
Plugging in the numbers gives you a ball‑park sample size to aim for.
Exam Tips for 3.2 Sampling 🧠
- Define sampling and explain why it’s used in market research.
- List at least three limitations and give a real‑world example for each.
- Show how to calculate a sample size using the formula above.
- Use the sampling error concept to explain why results are estimates.
- When answering, keep sentences short, use bullet points, and include emojis to illustrate points.
Good luck! Remember, the key is to show you understand both the why and the how of sampling. 🎯