A town council wants to know how much the public library is being used. They give questionnaires to everyone in the library every Thursday afternoon for a month. Why is this sample biased?
This may be a time when the library is unusually busy
Is the data discrete or continuous? The numbers of people using a supermarket each day in one month were: 123, 179, 235, 189, 207, 199, 145, 154, 198, 132, 207, 298, 188, 181, ...
discrete
A school wants to investigate the type of food students each at lunchtime. There are 1500 students at the school. Suggest a sensible number of students to be sampled.
10% of 1500 = 150
Decide whether it is primary or secondary data: "Percentage of the Indian population that used the Internet in 2019"
Secondary data
Decide whether it is primary or secondary data: "The percentage of people who write with their right hand"
primary data
A hospital wants to know the ages of people in the local area. They put questionnaires in the local pet shop. Why will this give a biased sample?
The fraction of the sample consisting of children is likely to be greater than general population: children like pet shops
Your experience on this site will be improved by allowing cookies.