Example 4

Determine the correct data type (quantitative or qualitative) and indicate whether quantitative data are continuous or discrete.

a.The number of pairs of shoes you own -

b.The type of car you drive -

c.The distance it is from your home to the nearest grocery store -

d.The number of classes you take per school year -

e.The type of calculator you use -

f.Weights of sumo wrestlers -

g.Number of correct answers on a quiz -

h.IQ scores -

Sampling

Gathering information about an entire population is often impossible, instead we use a sample of a population.

A sample should have the same characteristics as the population it is representing. Various methods are used:

Simple Random Sampling:

Example:

Stratified Sample:

Example:

Cluster Sample:

Example:

Systematic Sample:

Example:

Convenience Sampling:

Example:

The results of convenience sampling may be very good in some cases and highly biased (favor certain outcomes) in others.

With Replacement or Without Replacement

With Replacement:

Example: In a college population of 500 people, suppose you want to pick a sample of 10 randomly for a survey. For any particular sample of 500, if you are sampling with replacement

the chance of picking the first person is _________________

the chance of picking a different second person for this sample is _____

the chance of picking the same person again is _________________(very low).

Without Replacement:

Example: In a college population of 500 people, suppose you want to pick a sample of 10 randomly for a survey. For any particular sample of 500, if you are sampling without replacement

the chance of picking the first person is _______________________

the chance of picking a different second person for this sample is _____________

there is no chance of picking the same person again.