UNIT 4 : Study Procedures

The number of times data are collected (from the same participants)

Overall approach used in the study.

Activities and tools used to collect data.

- The study can be replicated by other scientist (others can redo)

• - More tied to procedures
• - What you see is a function of what you did

• - The findings can be generalized to the intended population. (can be applied to another group) 
• -Less tied to procedures

(manipulation of independent variable)

• 1- History
• 2- Maturation
• 3- Selection
• 4- Testing (pretest)
• 5- Instrumentation (scores)
• 6- Regression (away from mean)
• 7- Mortality (drop-outs)

• 1- Multiple treatment Interference
• 2- Reactive Arrangements (Hawthorne effect: in that participants know about a research experiment)
• 3- Experimenter Effects
• 4- Pretest sensitization (can tell people what is to come)

Interval: Randomly select participants, randomly assign into groups, and use a control group

External: Ensure that researchers do not effect outcome

Factors that can decrease the internal validity of a study.

• Control by:
• -Ignoring any variable that is unrelated to the dependent variable being measured.
• -Use of randomization that the effects of many different potential sources of variance can be controlled. 

Also by Matching, using homogeneous groups, and analysis of covariance (ANCOVA)

Order of occurrence (before, after) (this, that)

Presence of cause and effect.

Ex. Because he gives you a ring (before), you will get married (after).