Issues with Experiments Flashcards
What is a correlational design?
Consists of two continuous variables, both measured at interval or ratio scale.
what does “r” represent?
A correlation
What are some issues that impact Correlation?
Restriction of range (results can be misleading or incorrect when the measure has a restriction of range issue), lack of variability in responses, Ceiling effect and floor effect.
what is a floor effect?
An experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the low end of their possible distribution
What is a ceiling effect?
an experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the high end of their possible distribution.
What is a T-Test?
a statistical test used to evaluate the size and significance of the difference between 2 means.
What is a maturational threat to internal validity?
A change in behaviour that emerges more or less spontaneously over time
What are history threats to internal validity?
Alternative explanations are examples of history threats, which result from a ‘historical’ or external event that affects most members of the treatment group at the same time as the treatment making it unclear where the change originated
What are regression threats to internal validity?
Regression threats only occur in a prettest/posttest and only when a group has an extreme score at prettest. The direction of the score will travel back towards the middle following this extremely high or low score.
What are attrition threats to internal validity?
Losing people from a study. Attrition becomes a problem when it is systematic; that is, when only a certain kind of participant drops out.
What are testing threats to internal validity?
subtypes are practice effects and fatigue effects. Refers to the change in the participants as a result of taking a test (dependent measure) more than once.
what are Instrumentation (decay) threats to internal validity?
occurs when a measuring instrument changes over time.
what are null effects?
when the independent variable did not make a difference on the dependent variable, there is no signifiant covariance.
why might an experimenter get a null result?
Weak manipulation, Insensitive measures, and ceiling or floor effects.
Why do researchers replicate studies?
No study is perfect and there is no guarantee that findings are true and a single study does not prove anything. So researchers replicate to ensure reliability of results.
