assess crosstalk in RCT. Xinguang Chen Din Chen. MD, PhD, Professor PhD, Professor. Univ. of Florida Univ. of Rochester. 2014 APHA, Nov 16-19, New ...
Random-pairing bootstrap and mutual informational correlation to assess crosstalk in RCT Xinguang Chen MD, PhD, Professor Univ. of Florida
Din Chen PhD, Professor Univ. of Rochester
2014 APHA, Nov 16-19, New Orleans
RCT as Gold Standard • Strict to evaluate the effect of an intervention – Medicine – Behavioral
• Control potential confounding effects – Background – Attentional – Any other factors
2014 APHA, Nov 16-19, New Orleans
Threats to RCT for Educational/Behavioral Intervention • Fidelity of information delivery – Interventionist bias – Environmental differences
• Contamination through crosstalk – Purposeful information exchange between intervention and control – Incidental exchange
• Within group information exchange 2014 APHA, Nov 16-19, New Orleans
Difficulties in Assessing the Information Exchange • Do not know who exchanged what with whom – Issues related to human subject protection – Costly to collect data
• No methods are directly available to assess the impact – The relationship of information exchange between two persons is complex – Linear correlation is often inadequate 2014 APHA, Nov 16-19, New Orleans
Linear Correlation
X
Y Nov 16-19, New Orleans 2014 APHA,
Mutual Information • Let X and Y be two random variables • The dependence between X and Y:
• MI can take any form • 0 ≤ MI ≤ infinitive
2014 APHA, Nov 16-19, New Orleans
Informational Correlation RI • How to make MI look like R? o A number of researchers attempted various methods
• Method by Mathematics Encyclopedia
• For normal distributed data, we have: www.encyclopediaofmath.org/index.php/information-correlation-coefficient
2014 APHA, Nov 16-19, New Orleans
RPB for Assessing Informational Correlation
2014 APHA, Nov 16-19, New Orleans
The Flowchart for Random PairingBootstrap Informational correlation method for assessing crosstalk
Chen X Univ. Florida
Chen D Univ. Rochester
2014 APHA, Nov 16-19, New Orleans
Simulation Study 1 • Computer-generated data with bivariate normal distribution (n=500) • With known linear relationship – R = 0.00, 0.10, 0.20, 0.50, 0.88
• Varying bootstrap sample sizes – 50, 100, 150, 200, and 250
2014 APHA, Nov 16-19, New Orleans
Estimated RI(95%) CI with the RPB Method
2014 APHA, Nov 16-19, New Orleans
Conclusions for Study 1 • Informational correlation can reflect linear correlation with RPB method • The larger the Bootstrap sample, the close the RI to R, and the narrow the 95% CI of RI • N=250 looks like safe sample size for bootstrap
2014 APHA, Nov 16-19, New Orleans
Simulation Study 2 • Computer generated data with two known relationship (N=500)
• x~N(0, sigma2), -5 ≤ x ≤ 5 • b=2.0, sigma=2.0 2014 APHA, Nov 16-19, New Orleans
Estimated RI(95%) CI with the RPB Methods
2014 APHA, Nov 16-19, New Orleans
Conclusions for Study 2 • RI is a method to measure non-linear correlation which regular linear correlation R cannot with the RPB method • Pearson linear correlation can extract the linear part of the two relationships with the RPB method
2014 APHA, Nov 16-19, New Orleans
Analysis of Empirical Data • Longitudinal data from a 3-arm RCT • Participants: Bahamian youth – Intervention 1: – Intervention 2: – Control:
N=497 N=436 N=427
• Data set – Baseline, 12 months and 24 months
2014 APHA, Nov 16-19, New Orleans
Intervention Variables • HIV knowledge – Scale scores, 0-14
• Self-efficacy in condom use – Scale scores, 0-5
• Condom use skills – Scale scores, 0-8
2014 APHA, Nov 16-19, New Orleans
RI(95%) CI for Within-Group Communication
2014 APHA, Nov 16-19, New Orleans
RI(95%) CI for Between-Group Crosstalk
2014 APHA, Nov 16-19, New Orleans
Conclusions • RPB method is valid to generate data for assess information exchange • Informational correlation can be used to measure nonlinear relationship without assumption of the underlying relationship • Cross-talk is an issue for behavioral intervention
2014 APHA, Nov 16-19, New Orleans
Questions and Future Research • More studies to validate the RPB and informational correlation method in different settings – Experimental, simulation – Observational
• How to adjust the crosstalk in RCT given RI? • Sample size and power in research design
2014 APHA, Nov 16-19, New Orleans
Presenter Disclosures Xinguang Chen
I have no relationships during the past 12 months to disclose
