Week 7 Lecture Flashcards
What does correlational research do?
Quantifies the strength of the relationship between two or more variables.
Cross-sectional design in developmental research is differential research
Cross-Sectional and Longitudinal Research
Cross-sectional designs are faster:
Can test many age groups simultaneously.
But cohort effects can be a problem:
Defined as “shared life experiences of people of a given age that lead them to behave similarly to others their age and different from people of other ages”.
Longitudinal designs are essentially time-series designs.
Would prefer longitudinal designs, but…
Can correlations be used for prediction?
Yes.
Can correlation prove a theory?
No but it may negate it.
Can correlations establish causation?
No.
What do differential research methods do?
Compare two or more preexisting groups.
What research is differential research similar to?
Correlational and experimental research.
What research is differential research conceptually similar to?
Correlational research
Why is differential research conceptually similar to correlational research?
Variables measured, but not manipulated.
Are cross-sectional designs faster?
Yes, because they can test many age groups simultaneously.
Can cohort effects be a problem with cross-sectional designs?
Yes, “shared life experiences of people of a given age that lead them to behave similarly to others their age and different from people of other ages”.
What are longitudinal designs essentially…
Time-series designs.
What is preferable; longitudinal designs or cross-sectional designs?
Longitudinal.
Can correlational or differential research establish causation?
No.
Is correlational or differential a higher level of constraint?
Differential.
Why is differential a higher level of constraint than correlational?
The researcher can select the comparison group(s) to control at least some of the potential confounding variables, thus providing stronger evidence for a theory.
When do we use the correlational method?
When we are interested in knowing the strength of a relationship for predictive purposes. Often included to help interpret the primary findings of a study.
When do we use differential research?
When the manipulation of an independent variable is impractical, impossible, or unethical.
What is correlation coefficient?
A statistic indicating the degree to which two variables are related to one another in a linear fashion.
What is the key requirement for a correlational coefficient?
The key requirement being that we obtain scores on the two variables of interest for each participant.
What is the most common correlation coefficient?
Pearson correlation coefficient, r, is the most common.
r ranges from -1 to +1.
What does r (in the pearson correlation coefficient) range from?
+1 to -1.
What does the sign represent in the correlation coefficient?
The direction; positive or negative.
Can any relationship be portrayed graphically on an x and y axis?
Any relationship between two variables can be portrayed graphically on an x and y axis.
For each participant we can plot their combined x and y score and this equals a…
Scatter plot
What would a curvilinear relationship?
Calculation an r value would give a score of 0; very misleading.
What does p value provide us with?
The p value provides us with a measure of reliability
What are three factors that may inflate or deflate r artifically?
Restricted range.
Outliers.
Correlation and causality.
