Unformatted text preview: STA 2023 - Holbrook Understanding Randomness
Experiments and Observational Studies
Chapter 13 11_12_13 - 1 STA 2023 - Holbrook Understanding Randomness
(Pages 289291) 11_12_13 - 2 Randomness
STA 2023 - Holbrook 1. Using a random number table or a random
number generator, we can truly select a
2. Random Sample A sample is a random sample if each element
(i.e. person) in the population has an equally
likely chance of being selected. (Also called a
simple random sample (SRS). See Chapter 12.)
simple 3. Try taking a random sample in class.
11_12_13 - 3 STA 2023 - Holbrook Sample Surveys
Chapter 12 11_12_13 - 4 Key Terms
STA 2023 - Holbrook 1. Sample Survey A questionnaire given to a small group of people in
the hope of learning something about the population.
the 2. Representative Sample A sample is said to be representative if it exhibits
characteristics of the population.
characteristics 3. Biased Sample A sample is biased if it does not represent the
population in some important way.
population 4. Sampling Frame A list of individuals from which the sample is drawn. 11_12_13 - 5 Sampling Techniques
STA 2023 - Holbrook 1. Simple Random Sample (SRS) A sample is a SRS if each element (i.e. person) in
the population has an equally likely chance of being
selected. 2. Stratified Random Sample Divide the elements (i.e. people) into homogeneous
groups (strata) and take a SRS.
groups 3. Cluster Sample Group the population into small clusters, take a SRS
of clusters, and observe everything in the clusters.
of 11_12_13 - 6 Sampling Techniques (continued) STA 2023 - Holbrook 4. Systematic Sample Randomly select an element (i.e. a person) and then
select every kth element thereafter.
select 5. Multistage Sample Using a combination of these above methods 11_12_13 - 7 STA 2023 - Holbrook Experiments and Observational Studies
Chapter 13 (Pages 329332) 11_12_13 - 8 Key Terms
STA 2023 - Holbrook 1. Observational Study A study in which subjects are observed. 2. Experiment A study that assigns subjects randomly to
treatments. 11_12_13 - 9 ...
View Full Document
- Fall '11
- Statistics, Holbrook