Matching Summarize a Matching is defined as the process of selecting controls so that they resemble the cases with regard to certain characteristics The goal of matching is to create similar distributions between cases and controls with regard to certain characteristics Matching can be used to Adjust for potential confounding factors Increase precision of estimate
n Matching is defined as the process of selecting controls so that they resemble the cases with regard to certain characteristics n The goal of matching is to create similar distributions between cases and controls with regard to certain characteristics n Matching can be used to n Adjust for potential confounding factors n Increase precision of estimate Matching Summarize
Matching Types a Individual level matching For each case in the study one or more controls are selected with identical(similar) characteristics as the case a Frequency, or group, matching Select controls so that the proportion with a certain characteristic is identical to the proportion of cases with that characteristic
n Individual level matching n For each case in the study, one or more controls are selected with identical (similar) characteristics as the case n Frequency, or group, matching n Select controls so that the proportion with a certain characteristic is identical to the proportion of cases with that characteristic Matching
Matching Problems with Matching Difficult and expensive Cannot evaluate the effect of controlled variables May limit the ability to control for other variables Overmatching Controls resemble cases in terms of known and unknown characteristics. some of which may be associated with the disease
n Difficult and expensive n Cannot evaluate the effect of controlled variables n May limit the ability to control for other variables n Overmatching n Controls resemble cases in terms of known and unknown characteristics, some of which may be associated with the disease Problems with Matching Matching
Investigate Exampl oe e the association between occurrence of Eosinophilia-myalgia syndrome (EMs)and Ingestion of L-tryptophan e Background e conduct o results EPIDEMIOLOGY AN EALTH STATISTI
Investigate Example | the association between occurrence of Eosinophilia-myalgia syndrome(EMS) and Ingestion of L-tryptophan. ] Background | conduct | results EPIDEMIOLOGY AND HEALTH STATISTICS 1957 卫
Investigate Example Background EMS was first recognized in october 1989.it occurs predominantly in women and is relatively rare. when astute physicians determined that three people with unexplained myalgias and eosinophilia had consumed L-tryptophan. Prompt response by health departments quickly led to case-control studies the results of which suggested that ingestion of L-tryptophan was the cause of ems
Investigate Example Background EMS was first recognized in October 1989, it occurs predominantly in women and is relatively rare. when astute physicians determined that three people with unexplained myalgias and eosinophilia had consumed L-tryptophan. Prompt response by health departments quickly led to case-control studies,the results of which suggested that ingestion of L-tryptophan was the cause of EMS