1.3 Experimental Design

Question 1

Designing a Statistical Study

Answer 1

1. Identifying the variables of interest and the population of the study
2. Develop a detailed plan for collecting data. If you use a sample make sure it is representative of the population.
3. Collect the data.
4. Describing the data using descriptive statistics techniques.
5. Interpret that data and make decisions about the population using inferential statistics.
6. Identify any possible errors.

Question 2

Observational Study

Answer 2

• A researcher observes and measures characteristics of interest of part of a population.
• Researchers observed and recorded the mouthing behavior on non food objects of children up to three years old.

Question 3

Experiment

Answer 3

• A treatment is applied to part of a population and responses are observed.

Question 4

Simulation

Answer 4

• Uses a mathematical or physical model to reproduce the conditions of a situation or process.
• Often involves the use of computers
• Automobile manufacturers use simulations with dummies to study the effects of crashes on humans.

Question 5

Survey

Answer 5

• An investigation of one or more characteristics of a population.
• Commonly done by interviews, internet, phone, mail.
• Can be open or closed questions.

Question 6

Census

Answer 6

• A count or measure of an entire population.
• Often difficult and costly to perform.

Question 7

Sampling

Answer 7

• A count or measure of part of a population.
• To ensure unbiased results the researcher must ensure that the sample is representative of the population.

Question 8

Sampling Error

Answer 8

Difference between the results of a sample and those of the population.

Question 9

Simple Random Sample

Answer 9

Every possible sample of the same size has the same chance of being selected.

Question 10

Stratified Sample

Answer 10

• Divide a population into groups (starts) and select a random sample from each group.

Question 11

Cluster Sample

Answer 11

• Divide the population into groups (clusters) and select all the members in one or more, but not all the clusters.

Question 12

Systematic Sample

Answer 12

• Metal detector example
• Choose a starting volume at random. Then choose every Kth member of the population.

Question 13

Convince Sample

Answer 13

• Choose any members of the population that are easy to get.
• Often leads to biased studies (not recommended)