Advanced Research Methods

1
Advanced Research Methods

• Alternative Correlational Techniques

2
Point-Biserial Correlation

• Dichotomous variable and a continuous variable
• Use Pearson correlation formula
• Example X Sex, Y Income
• Males 48,597.20
• Females 41,892.40

3
Point-Biserial and t

• Tests are equivalent
• Independent groups t-test
• t(8) -0.97, p 0.36
• Test of the b-weight
• t(8) -0.97, p 0.36

4
Phi Coefficient

• Both variables are dichotomous
• Use Pearson correlation formula
• Example X Sex, Y Terminal Degree
• f -0.23 (f2 0.05)

5
Phi Coefficient Chi-Square

• Could have examined the relationship using
  chi-square
• Phi will equal the square root of (c2/N)

6
Example
7
Correlations for ranked data

• Spearmans rho
• Use Pearson correlation formula
• Kendalls tau coefficient
• Based on number of inversions

8
Contingency Tables with Ordered Variables

• Correlate the two variables using the most
  appropriate correlational technique

9
Example