2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

D'Auria, T. (2013, Jan 19). How to Create a Random Sample in Excel (in 3 minutes!). Check Your Assumptions. [Video]. YouTube. Retrieved March 27, 2021 from https://youtu.be/q8fU001P2lI

Stratified Random Sample The population is first divided into non-overlapping subgroups (called strata). Strata are subgroups that are similar (homogeneous) based upon some characteristic of the group members. Once you have your strata, use simple random samples to select from each subgroup (or stratum). Quiz

Advantage: It allows you to make more accurate inferences about a population than does simple random sampling.

Example: We want to estimate the average cost of malpractice insurance for doctors in a particular city. We could view the population of all doctors as falling into one of four subgroups: 1) surgeons, 2) internists and family practitioners; 3) obstetricians, and 4) all other doctors.

Now let's look at a video on YouTube using Excel the create a stratified random sample!

D'Auria, T. (2013, Jan 19). How to Create Stratified Random Sample in Excel. Check Your Assumptions. [Video]. YouTube. Retrieved from https://youtu.be/70qEBD3-88U

Cluster Sampling Cluster sampling divides the population of interest into non-overlapping subgroups, called clusters. Clusters are then selected at random, and all individuals in the selected clusters are included in the sample. Example: A school administrator wants to select a sample of 75 seniors to participate in a survey. There are 24 senior homerooms, each with approximately 25 students. He could randomly select 3 senior homerooms and then include all the students in the selected homerooms in the sample. Cluster sampling is NOT the same as stratification!

There is a difference between cluster sampling and strata sampling. When sampling from a strata, only a few are selected from each sample. If you use cluster sampling, complete clusters will be selected.

Advantage: Saves time and money.

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