What is a subject?
a term used to describe individuals studied in an experiment when they are people.
What is a treatment?
Any specific experimental condition applied to subjects in an experiment.
What is a factor?
The explanatory variable in an experiment.
What are advantages of experiments over observational studies?
- Experiments allow for the study of effects of different treatments of interest.
- Experiments allow for the subjects’ environments to be controlled which lets factors remain constant that are not of interest.
- The combined effects of several factors can be studied simultaneously in an experiment.
What are the advantages of experiments conducted in a lab?
Experiments conducted in a lab are exposed to less variable conditions than field experiments and experiments involving human subjects.
When is a simple experiment design more likely to work well?
In a controlled environment.
What happens when a simple experiment design is used in an environment with more variable conditions?
A simple design used where more variable conditions are present often result in worthless result due to the presences of confounding or lurking variables.
What are the principles of experimental design?
- Control the effects of working variables on the response, most simply by comparing two or more treatments.
- Randomize- use impersonal chance to assign subjects to treatments.
- Use enough subjects in each group to reduce variation in results.
What does it mean for something to be statistically significant?
The observed effect is so large that it would rarely occur by chance.
True or false?: A statistically significant association from a well designed experiment implies causation.
True
What is a completely randomized design?
An experiment design in which individuals are assigned to treatments at random.
True or false?: Completely randomized designs can compare more than one treatment and have more than one factor.
True.
What is the simplest statistical experiment design?
Completely randomized designs.
True or False?: Completely Randomized designs allow for comparison and randomization, but does not allow for an adequate number of subjects.
False. Completely Randomized designs allow for comparison, randomization, and an adequate number of subjects.
In what circumstance could a completely random design not be suitable?
When dealing with substantial individual-individual variability or potential confounding variables.
What is a block design?
A design in which individuals are organized into blocks based on a shared pre-exisiting characteristic and then are randomly assigned to treatments within each block; Random assignment occurs in each block.
True or false?: Blocking decreases control over the experiment.
False. Blocking is a form of control.
What is the best characteristic to base blocks on?
It is wise to form blocked based on the most important and unavoidable sources of variability among individuals.
What is a matched pairs design?
A design that compares two treatments, either by using a series of individuals that are closely matched two by two or by using each individual twice.
When is a matched pairs design usually used?
When substantial differences between individuals exist or are suspected.
True or False?: Matched pairs design allows for complete randomization.
False. Matched pairs design allows for randomization, but it is not complete because the randomization only occurs within each pair.
Match Case-control and matched pairs to the following terms.
1. Observational study
2. Experiement
- Case-Control
- Matched Pairs
What is accuracy?
How close values are to the true value.
What is precision?
How close values are to eachother.
