Vocabulary
A treatment that has no effect given so all groups experience the same conditions.
What is placebo
The variable(s) that we control, change or impose in an experiment.
What is explanatory or factor?
The experimental units assigned to a baseline treatment level, either the default or a placebo treatment.
What is a control group
This type of statistical design that we have learned is the only one where we can (officially) show a causal relationship.
What is an experiment?
A group of researchers analyzed data from 3 different studies that followed high school students attendance and mental health.
Identify whether this was an observational study or an experiment. If it is an observational study, identify whether it is retrospective or prospective.
A retrospective Study
This procedure manipulates factor levels, randomly assigns subjects and and compares responses of all subject groups across treatment levels.
What is a experiment
A study where no treatments are applied, in which subjects are followed to observe future outcomes
What is a prospective study
Occurs when a subjects reacts favorably to a treatment when in fact the subject has been given a fake treatment.
What is placebo effect
DAILY DOUBLE
9/3
A variable that is associated with both y and x that makes it appear that x may be causing y.
In a test of roughly 200 older men and women, those with moderately high blood pressure did worse on tests of memory and reaction time than those with normal blood pressure.
Identify whether this was an observational study or an experiment. If it is an observational study, identify whether it is retrospective or prospective.
What is a prospective observational study
The process, intervention, or other controlled circumstances applied to randomly assigned experimental units.
What is Treatment
The variable whose values are compared across different treatments.
What is the response variable?
This occurs in an experiment when any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups.
What is blinding, single blind, double blind
A way to reduce variation by placing units in groups based on one variable they have in common.
What is blocking
Ms. Hannon is part of an experiment to determine the effectiveness of a Covid 19 vaccine. The company wants to test a normal size dosage and a dosage twice the normal size against a control group. It wants to give each of these 3 different ways: the first way will give the dose all at once, the second way will give 1/2 the dose the first week and the second half a week later, the third way will divide the dose into 3 parts and give each 1/3 of the dose over 3 weeks.
Describe the factors, levels and treatments of this experiment.
This experiment has 2 factors (dosage and delivery time), 3 levels each (dosage: placebo, reg. dose, 2x reg dose; delivery: 1 week, 2 weeks, 3 weeks) for 9 total treatments.
A study where the researcher is not able to control (1) how subjects are assigned to groups and/or (2) which treatments each group receives. No manipulation of factors is used
What is observational study
An observed difference that is too large to likely have occurred naturally.
What is statistically significant?
An experiment where both those who could influence the results and those who evaluate the results are unaware how the subjects are allocated to the treatment groups.
What is double-blind experiment
When subjects who are similar in ways not under study may be matched and compared with each other on the variable of interest.
What is Matched Pair design
Some schools teach reading using phonics (the sounds made by letters) and others using whole language (word recognition). Suppose a school district wants to know which method works better. Suggest a design for an appropriate experiment.
Answer should include 2 treatments, randomization of subjects for each treatment, and replication of treatments (multiple subjects).
Answer should also include means of determining "which method works better" and should also mention being a single blind experiment.
A study in which subjects are selected and their previous conditions or behaviors are observed.
What is a Retrospective Study
The two main classes of individuals who can affect the outcome of the experiment.
What are those that could influence the results (subjects, treatment administrators), and those that evaluate the results (judges, treating physicians etc.)
This process helps balance all the variables we cannot possibly control for.
What is randomization
When we are uncertain which of two variables is causing an effect.
What is confounding
These are the 4 main principles of Experimental Design
What are Control, Randomize, Replicate and Block/Compare