Lesson Two: Types of Experiments

Question 1

Stratified:

Answer 1

Items to be sampled are organized in groups of similar items (called strata), then a simple random sample is drawn from each group.

Question 2

Cluster or Block Sample:

Answer 2

Taking all items in one or more randomly selected clusters, or blocks. You’d take an SRS of the clusters, then take the whole population within those random clusters.

Question 3

Simple Random Sample:

Answer 3

Best method! Must have a list of all the items in the population to enter into a random number generator.
Excel: =RANDBETWEEN(smallest integer, largest integer)

Question 4

Systematic:

Answer 4

This is when every xth item in the population is selected to be part of the sample, beginning at a RANDOM starting point. This works best when the items are in a random, but SEQUENTIAL ordering.

Question 5

Convenience Sample:

Answer 5

Selecting items that are relatively easy to obtain and does not use random selection to choose the sample. This sample always brings bias.

Question 6

Quantitative Variables:

Answer 6

Provide measurement information on each individual (or item) in the study. They represent things that are numeric in nature: things that are measured. They often include units of measurement along with the quantitative value of the measurement.

Ex. heights of children measured in inches, or weight of adults in pounds.

EASY MEMORY TRICK:
If you can double the numeric measurement and it’s arithmetically sound, it’s quantitative data.

Ex. the weight of an adult that’s 120 pounds vs. weight of an adult that’s 240 pounds. This can be logically doubled!

Question 7

Categorical Variables:

Answer 7

Allow us to place each individual (or item) into a specific category. These are labels, and it doesn’t make sense to do arithmetic with them.

Ex. Gender of a newborn child, brand of phone used, area code of a telephone number.