Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 8524715

Matching.

M C Costanza
View original source ↗Export metadata ↓

Abstract

Matching is an intuitively appealing design strategy for ensuring balance on one or more potential confounding variables, usually either among subjects who were exposed or unexposed to a suspected risk factor for disease in a cohort study or between diseased and nondiseased subjects in a case-control study. But does matching always automatically "control" confounding and is it always as good a strategy as it seems? It is the intention of this review to shed light on these questions primarily through illustrative examples of the effects of matching on the validity of point estimates of the odds ratio between exposure and disease status in both types of study designs. It is seen that the results of matching are more or less in line with expectations in cohort studies, but that matching can lead to unexpected results in case-control studies. In a case-control study, confounding is not automatically controlled by matching per se; rather, matching and a statistical analysis that properly accounts for the matching are needed to obtain a valid estimate of effect in a case-control study design.

Explore related subjects

Confounding Factors, EpidemiologicHumansMatched-Pair AnalysisOdds RatioResearch DesignRisk FactorsJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M C Costanza. 1995. Matching.. https://doi.org/10.1006/pmed.1995.1069

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1997

Requirement for accurate measurement of regurgitant stroke volume by the combined continuous-wave Doppler and color Doppler flow convergence method.

The examination conditions necessary for accurate measurement of regurgitant volume by the proximal flow convergence method applying a simple hemispheric equation remain uncertain. This study investigated the requirement for measuring regurgitant stroke volume from the combined continuous-wave and color Doppler proximal flow convergence approach. Twenty-five pulsatile flow rates were produced by driving five regurgitant stroke volumes ranging from 30 to 70 ml/beat through planar orifices with cross-sectional areas ranging from 0.10 to 1.0 cm2. Four different shaped orifices (circular, rectangular with a major/minor axis ratio 2:1, slitlike with a major/minor axis ratio of 8:1, and square) having identical orifice areas (0.5 cm2) were examined. Regurgitant volume (RV) was estimated from the combined continuous-wave and color Doppler approach according to the previously described equation RV = 2 pi x (r max)2 x AV x (TVI/Vmax), where r max is maximal radial distance, AV is aliasing velocity, TVI is time velocity integral of regurgitant jet, and Vmax is peak velocity of regurgitant jet. Plotting the difference between actual and calculated RV versus radial distance of the proximal convergence shell for each flow rate from circular to rectangular orifices yielded curves conforming to a curvilinear function that crossed the point of zero difference at 1.0 cm. However, in the slitilke orifice, a more remote distance (1.6 cm) is required for the best agreement. Actual regurgitant stroke volume can be estimated well by the combined continuous-wave Doppler and proximal flow convergence method applying a simple hemispheric equation if an aliasing velocity is used that results in a radial distance of at least 1.0 cm.

Confounding Factors, Epidemiologic↗
PubMed1997

Is there a benefit to episiotomy at operative vaginal delivery? Observations over ten years in a stable population.

OBJECTIVE: Our purpose was to examine the association between maternal vaginal and perineal morbidity and episiotomy performed at operative vaginal delivery. STUDY DESIGN: We obtained data from 2041 consecutive operative vaginal deliveries and compared yearly rates of episiotomy, lacerations, and potential confounders with linear regression and stratified analyses. RESULTS: Between 1984 and 1994 the use of episiotomy for operative vaginal deliveries fell significantly (93.4% to 35.7%, R2 = 0.85, p = 0.0001). This change was associated with a rise in the rate of vaginal lacerations (16.1% to 40.0%, R2 = 0.80, p = 0.0002), a decrease in the rate of fourth-degree lacerations (12.2% to 5.4%, R2 = 0.62, p = 0.004), but no significant change in the rate of third-degree lacerations. These associations held in separate analyses stratified by parity and type of instrument used for delivery. The prevalence of other previously reported risks for perineal morbidity did not change during the study period. CONCLUSION: At our institution a statistically and clinically significant reduction in the use of episiotomy for operative vaginal deliveries was not associated with a change in the rate of third-degree lacerations but was associated with an increase in the rate of vaginal lacerations and a decrease in the rate of fourth-degree lacerations.

Confounding Factors, Epidemiologic↗
PubMed1997

Observations on the neglected concept of intervention in nursing research.

In this paper I will examine the concept of researcher intervention in nursing research. I will suggest that the concept is essentially problematic for both positivist and qualitative researchers, which may have some bearing upon its relative neglect as an area for discussion. I will examine the redundancy of the more popular moral frameworks in dealing with the problems raised by intervention and suggest that nursing research, being 'messy', requires the articulation of a more reflexive and contextual approach. This applies both to moral justification and to more pragmatic methodological issues. In the paper I suggest that humanistic action research, informed by recent feminist thinking, has potential to produce a more creative and clinically relevant future for nursing research than is currently so.

Confounding Factors, Epidemiologic↗