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SOC202 MARCH 20, 2012

CORRELATION

- Entering a new unit ā measuring ass

- We often want to know the existence and trhe strength of reln b/w two ariables

- What is their co rel

- Correlation is degree of ass

- As edu increases mental health increases

Contd

- Finding a rel exist not indcite degree of ass all say is relationship

- Not know what causes what, see an ass not causation

- Vusualize differences in stgrentth of correlation by means of a scatterplot

Scatter plot

- Graph scores on x and y are scatter

- X is inde

- Y is dep

- Each dot on scattergram is a case in he data set

- The dot is placed at the intersection of the cases scores x and y

Example

- Percent college and voter turnout, percent increases turnout incrases

Regression

- Line of best fit clostest to a scater points

- Greater extetn dots cludtered line stronger reltn

- This one is weak to moderate

- Know it is positive rel

- Correlation is occurring

- Described p or n higher scores higher on other a negative is opp high one mean low on other

Scatter and line

- Inspection of scatter plot firstthiing two interval level

- Level of measurement determine the test

- Interval is correlation or ratio,

- Relation must be straight line, linear

Curvilinear correltion

- Not all reln is straight