Question

A restaurant manager requests a random sample of $100$ customers to fill in the following questionnaire.

What kind of data-collection method does the manager use?

Accepted Answer

Statistics is a branch of mathematics that involves collecting, organising, interpreting, presenting and analysing data. Based on the studies of data obtained, people are able to draw conclusions, make decisions and plan wisely.

When the group we want to collect data from is large, we often randomly select a smaller group as a representative of the entire group. This method of data collection is called random sampling. Random sampling makes data collection faster, less costly, and easier to analyse since the data population is smaller.

Normally, there are four ways, the random sampling can be done:

a) Taking Measurements in Experiments
In biology and engineering, we can set up control experiments to take measurements from random samples of particular objects of interest.

Examples: (i) The yield of cross-fertilisation of different types of rice can be measured by using samples from a patch of rice field.
(ii) The lifetime of a certain battery can be tested in a quality-control laboratory by using a small random sample of batteries.

b) Observing Outcomes of Events
Some data, such as air pollution levels and bird migration paths, are observed through real-life situations.

Examples: (i) Air pollution levels are observed by taking random air samples.
(ii) Bird migration paths are traced by tagging a sample population of birds with identification numbers.

c) Conducting Surveys
We usually conduct a survey to gather personal data and public opinion by requesting sample populations of target groups to complete a questionnaire. The survey may be conducted through face-to-face interviews, telephone interviews, postal surveys, or Internet surveys.

(i) The United States Census is a $100 %$ population survey that is conducted once every 10 years.
(ii) Customer satisfaction surveys taken by random samples of customers are very common in the service sector.

d) Reading Statistical Publications
Some data such as economic conditions and the population of a country are obtained by conducting large-scale surveys that cannot be done by individuals or small companies. We can obtain these types of data from official statistics published by government organisations.

Examples: (i) www.indiastat.com is a useful website for India statistics.
(ii) The United Nations Statistical Yearbook contains a wide range of international economic, social, and environmental data.

In this case, the manager used a survey form and collected data from $100$ customers at random.

Therefore, the manager used the method "conducting surveys".

Vistor Chow wal keung | RC Yadav Solutions for Chapter: Data Handling, Exercise 1: EXERCISE

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