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Correlation is used to establish wither there is a relationship between two variables. This
measurement of the two variables does not involve any manipulation; therefore it is very useful
technique when variables cannot be manipulated for practical or ethical reasons.
Strengths of correlation;
Uses quantifiable measures of each of the two variables,
Gives information about the relationship between two variables clearly,
Strong correlations (positive or negative) can form the basis for further experimental
research to establish cause and effect.
Weaknesses of correlation;
Cause and effect cannot be established,
Findings can be misleading, as they can imply cause and effect relationships that do not
Anomalies can miscue the results.
Positive correlation - high values of one variable are associated with high values of the
other, the variables increase together.
Negative correlation high values of one variable are associated with low values of the
other, as one increases the other decreases.
Zero correlation there is no correlation between the two variables they are said to have
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+1.0 Perfect positive
+0.8 Strong positive
+0.5 Moderate positive
+0.2 Weak positive
0 Zero correlation
-0.2 Weak negative
-0.5 Moderate negative
-0.8 Strong negative
-1.0 Perfect negative
A correlation coeffiants refers to a number between -1 and +1 and states how strong a correlation is.
If the number is close to +1 there is a positive correlation, whilst alternatively if the number is close to
-1 then there is a negative correlation.…read more
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Null statement There will be no significant correlation between [variable 1]
(measured by [something]) and [variable 2] (measured by [something]).
Two tailed statement There will be a significant correlation between [variable 1]
(measured by [something]) and [variable 2] (measured by [something]).…read more