Choosing a Sample

There is more than one way to select a sample. When we cannot survey an entire population, we must choose a sample from the population. There is more than one way to select a sample. 1/7

Simple Random Sampling Each member of population has an equal chance of being chosen Ex. To survey 5 students, you draw the names of 5 kids in your class out of a hat. 2/7

Systematic or interval sampling Every nth member of the population is selected. Ex. At a light bulb factory, every 100th light bulb is tested to see how long it lasts. 3/7

Cluster Sampling Every member of a randomly selected group of the population is selected. Ex. Mrs. Manson chooses a random class and asks everyone in that class how much they think a dance ticket should cost. 4/7

Self-Selected Sampling Only members of the population who volunteer take part. Ex. Mlle. Jorgensen asks if anyone would like to complete a survey about environmental issues at Phoenix and 6 people volunteer. 5/7

Convenience Sampling Only members of the population who are convenient are sampled. Ex. For a survey about corner store purchases, only people coming out of the Jolly Giant are surveyed. 6/7

Stratified random sampling Some members of each group of the population are sampled, even if the groups are of different size. Ex. 100 people from each province are randomly chosen and asked “What does it mean to be Canadian?” 7/7