P.P. 7 Causal Research
Extraneous variables
Any variables that experimental researchers do not measure or control that may affect the dependent variable.
Validity
The extent to which the conclusions drawn from an experiment are true
Treatment:
The independent variable whose effect is being monitored.
3 types of Experiemental Design
1. Quasi - experimental 2. True 3. Time Series Difference: Randomization and control = VALIDITY
Spurious correlation
A mathematical relationship in which two or more events or variables are not *causally* related to each other (i.e. they are independent), yet it may be wrongly inferred that they are, due to either coincidence or the presence of a certain third, unseen factor. Q: Let's say that Macintosh's sales went up 45% the week following the Super Bowl. This sales increase is unprecedented in its history and unmatched by its competitors. Based on these findings, do you recommend buying ad time again next year? Why or why not? My A: I don't b/c what if the sales spike was totally unrelated to the ad? For instance, what if I told you that, the same week, Consumer Reports came out with its PC ratings and iMacs were rated "Superior". You've wasted $1.6 million and likely lost your job.
External validity
Extent to which a causal relationship found in a study can be expected to be true for the entire target population Lab experiments, control variables
Internal validity
Extent to which the research design accurately identifies causal relationships
Dependent variables:
Measures of effects or outcomes that occur as a result of changes in levels of the independent or causing variable(s)
Causal research
Studies that enable researchers to assess "cause-effect" relationships between two or more variables -Looking to predict future behavior.
Experimental Design
The symbols of experimental design: *O* = The measurement of a dependable variable. *X* = The manipulation, or change, of an independent variable. *R* = Random assignment of subjects (consumers, stores, and so on) to experimental and control groups. *E* = Experiment effect; that is, the change in the dependent variable due to the independent variable. -Time is assumed to be represented horizontally, on a continuum. -Subscripts, such as O1, or O2, refer to different measurements made of the dependable variable.
Independent variables:
Variables whose values are directly manipulated by the researcher
Causal Inference
We infer causality with: Experiments - where we manipulate one variable (X) and note its effect on another variable (Y) while controlling for all other extraneous variables.
