Passer chapter 5: Correlation and correlational research
Correlation: basic concepts
- Correlation is a statistical association between variables. A correlation exists between
two variables (X and Y) when te scores or values of X are associated with the scores
of values of Y.
- Correlational research involves examining potential associations between naturally
occurring variables by measuring those variables and determining whether they are
statistically related.
In correlational research, variabels are measured not manipulated!
Three possible sources of associations:
1 – X and Y are characteristics of the same people.
2 – X and Y are characteristics of different, but related, sets of people.
3 – X is a personal characteristic and Y is an environmental characteristic.
Positive and negative correlation
- Positive correlation means that higher scores or levels of one variable tend to be
associated with higher scores or levels of another variable.
- Negative correlation means that higher scores or levels of one variable tend to be
associated with lower scores or levels of another variable.
Measuring correlations – The correlation coefficient
- Pearson’s r
A statistic that measures the direction and strength of the linear relation between two
variables that have been measured on an interval or ratio scale.
Can range from -1,00 to +1,00
-1,00 = perfect negative correlation
+1,00 = perfect positive correlation
0 = no correlation
Correlation: basic concepts
- Correlation is a statistical association between variables. A correlation exists between
two variables (X and Y) when te scores or values of X are associated with the scores
of values of Y.
- Correlational research involves examining potential associations between naturally
occurring variables by measuring those variables and determining whether they are
statistically related.
In correlational research, variabels are measured not manipulated!
Three possible sources of associations:
1 – X and Y are characteristics of the same people.
2 – X and Y are characteristics of different, but related, sets of people.
3 – X is a personal characteristic and Y is an environmental characteristic.
Positive and negative correlation
- Positive correlation means that higher scores or levels of one variable tend to be
associated with higher scores or levels of another variable.
- Negative correlation means that higher scores or levels of one variable tend to be
associated with lower scores or levels of another variable.
Measuring correlations – The correlation coefficient
- Pearson’s r
A statistic that measures the direction and strength of the linear relation between two
variables that have been measured on an interval or ratio scale.
Can range from -1,00 to +1,00
-1,00 = perfect negative correlation
+1,00 = perfect positive correlation
0 = no correlation
