Correlation between Age and Monitoring on Risk Behaviors in Children
This study examines the impact of age and monitoring on risk behaviors in 12-year-old children. Results show the correlation between age and risk behaviors controlling for monitoring, as well as the correlation between monitoring and risk behaviors controlling for age.
Correlation between Age and Monitoring on Risk Behaviors in Children
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Presentation Transcript
Practice • N = 130 • Risk behaviors (DV; Range 0 – 4) • Age (IV; M = 10.8) • Monitoring (IV; Range 1 – 4)
How many risk behaviors would a child likely engage in if they are 12 years old and were monitored “1”?
How many risk behaviors would a child likely engage in if they are 12 years old and were monitored “1”? = 1.72 behaviors
How many risk behaviors would a child likely engage in if they are 12 years old and were monitored “4”?
How many risk behaviors would a child likely engage in if they are 12 years old and were monitored “4”? .51 behaviors
What has a bigger “effect” on risk behaviors – age or monitoring?
Significance testing for Multiple R p = number of predictors N = total number of observations
Significance testing for Multiple R p = number of predictors N = total number of observations
What is the correlation between age and risk controlling for monitoring? What is the correlation between monitoring and risk controlling for age?
Quick Review • Predict using 2 or more IVs • Test the fit of this overall model • Multiple R; Significance test • Standardize the model • Betas • Compute correlations controlling for other variables • Semipartical correlations
Testing for Significance • Once an equation is created (standardized or unstandardized) typically test for significance. • Two levels • 1) Level of each regression coefficient • 2) Level of the entire model
Testing for Significance • Note: Significance tests are the same for • Unstandarized Regression Coefficients • Standardized Regression Coefficients • Semipartial Correlations
Remember • Y = Salary • X1 = Years since Ph.D.; X2 = Publications • rs(P.Y) = .17
Remember • Y = Salary • X1 = Years since Ph.D.; X2 = Publications • rs(P.Y) = .17
Significance Testing • H1 = sr, b, or β is not equal to zero • Ho = sr, b, or β is equal to zero
Significance Testing sr = semipartial correlation being tested N = total number of people p = total number of predictors R = Multiple R containing the sr
Significance Testing N = 15 p = 2 R2 = .53 sr = .17
Significance Testing • t critical • df = N – p – 1 • df = 15 – 2 – 1 = 12 • t critical = 2.179 (two-tailed)
t distribution tcrit = -2.179 tcrit = 2.179 0
t distribution tcrit = -2.179 tcrit = 2.179 0 .85
If tobs falls in the critical region: • Reject H0, and accept H1 • If tobs does not fall in the critical region: • Fail to reject H0 • sr, b2, and β2 are not significantly different than zero
Practice • Determine if $977 increase for each year in the equation is significantly different than zero.
Significance Testing N = 15 p = 2 R2 = .53 sr = .43
Practice • Determine if $977 increase for each year in the equation is significantly different than zero.
Significance Testing • t critical • df = N – p – 1 • df = 15 – 2 – 1 = 12 • t critical = 2.179 (two-tailed)
t distribution tcrit = -2.179 tcrit = 2.179 0
t distribution tcrit = -2.179 tcrit = 2.179 0 2.172
If tobs falls in the critical region: • Reject H0, and accept H1 • If tobs does not fall in the critical region: • Fail to reject H0 • sr, b2, and β2 are not significantly different than zero
Remember • Calculate t-observed b = Slope Sb = Standard error of slope
Significance Test • It is possible (as in this last problem) to have the entire model be significant but no single predictor be significant – how is that possible?
Common Applications of Regression • Mediating Models Teaching Evals Candy
Common Applications of Regression • Mediating Models Happy Teaching Evals Candy
Mediating Relationships • How do you know when you have a mediating relationship? • Baron & Kenny (1986)
Mediating Relationships Mediator b a c DV IV
Mediating Relationships Mediator a IV 1. There is a relationship between the IV and the Mediator
Mediating Relationships Mediator b DV 2. There is a relationship between the Mediator and the DV
Mediating Relationships c DV IV 3. There is a relationship between the IV and DV