Chapter 4.2: Observational Study vs Experiment

Ethical Experiment

if not an ethical experiment then there cant be an experiment- observational study

Statistically Significant

if the observed difference in responses between the groups in an experiment is too large to be explained by chance variation in the random assignment

Blocking

if you have a known characteristic within your experimental units that you would expect to affect the response to the treatments- you must block -you must say why you are blocking -you can only compare results within each block

Inference (about population)

individuals taking part in the study are randomly selected form the larger population -about cause and effect- treatments are randomly assigned to experimental units

Matched Pairs Design

matched subjects (with known similarities) are used to compare a treatment or both treatments are done to the same subject

Explanatory Variable

("x" independent) helps explain or predict changes

Response Variable

("y" dependent) measures an outcome of a study

Four Principals of Experimental Design

-comparison: at the end of experiment -Random Assignment: experimental units to treatments -control: keep other variables constant, or have a control group -replication: enough experimental units -concluding inference: can only make inference about he population you selected from

Treatment

a specific condition applied to the individuals in an experiment

Experiment

deliberately imposes some treatment on individuals to measure their response

Single Blind Experiment

neither the subject or whoever is interacting with subjects knows who is receiving what treatment

Double Blind Experiment

neither the subject or whoever is interacting with the subject know who is receiving what treatment

Observational Study

observes individuals and measures variables of interest but does not attempt to infer the response

Confounding Variable

occurs if a variable other than the explanatory variable or response variable is associated with the explanatory and response variable

Factors

often used for explanatory variables, different categories of your treatment

Lurking Variable

something else that may be affecting your experiment

Experimental Units

the individuals of which the treatment is applied