Stats 2

Explain the difference between a simple random sample and a systematic sample. (Select all that apply.)

In a simple random sample, every sample of size n has an equal chance of being included. In a systematic sample, the only samples possible are those including every kth item from the random starting position.

Explain the difference between a stratified sample and a cluster sample.

In a stratified sample, random samples from each strata are included. In a cluster sample, the clusters to be included are selected at random and then all members of each selected cluster are included

Consider a completely randomized experiment in which a control group is given a placebo for congestion relief and a treatment group is given a new drug for congestion relief. Describe a double-blind procedure for this experiment.

Neither the patients nor those administering the treatments know which patients received which treatments.

What symbol is used for the standard deviation when it is a sample statistic? What symbol is used for the standard deviation when it is a population parameter?

Sample statistic: s. Population parameter: σ.

When computing the standard deviation, does it matter whether the data are sample data or data comprising the entire population? Explain.

Yes. The formula for s is divided by n − 1, while the formula for σ is divided by N.

What symbol is used for the arithmetic mean when it is a sample statistic? What symbol is used when the arithmetic mean is a population parameter?

statistic, x; parameter, μ

What are some benefits of such a procedure?

This process should eliminate potential bias from patient psychology regarding benefits of the drug .This process should eliminate potential bias from the treatment administrators.