Korean J Radiol.  2015 Apr;16(2):286-296. 10.3348/kjr.2015.16.2.286.

Propensity Score Matching: A Conceptual Review for Radiology Researchers

• Baek S
• Park SH
• Won E
• Park YR
• Kim HJ

• KMID: 2070172
• DOI: http://doi.org/10.3348/kjr.2015.16.2.286

Abstract

The propensity score is defined as the probability of each individual study subject being assigned to a group of interest for comparison purposes. Propensity score adjustment is a method of ensuring an even distribution of confounders between groups, thereby increasing between group comparability. Propensity score analysis is therefore an increasingly applied statistical method in observational studies. The purpose of this article was to provide a step-by-step nonmathematical conceptual guide to propensity score analysis with particular emphasis on propensity score matching. A software program code used for propensity score matching was also presented.

Keyword

Propensity score; Matching; Observational study; Indication bias

MeSH Terms

Female
Humans
Male
Middle Aged
*Propensity Score
Radiology/*methods
Research Design
Research Personnel
Software

Figure

• 

  Fig. 1 Distribution of propensity scores. A. Distribution of propensity scores among total study subjects (940 and 470 patients who had liver CT and liver MRI, respectively). B. Distribution of propensity scores after matching for age, gender, body mass index, lesion diameter, and history of cancer (293 pairs of liver CT and liver MRI).

• 

  Fig. 2 Q-Q plots of each covariate from 2 groups before and after propensity score matching.

• 

  Fig. 3 Plot of standardized differences in means before and after propensity score matching.

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