EVALUATION OF RESEARCH STUDIES Part I: Randomized Trials
PatriciaAhins Murphy,
CNM,
CG;rical practice is often based on the r&sutk of research. As a wsvlt, the abGity to evaluate a research report nittcaGy k vital. We warIt to incurcarate into ma&e thae Gndin~~sthat
selles of columns. we will review plinci& of researrh metbc&log,~ as they apply to the ec;l!uation of published studies; we begin with a discussion cat randomized trials. The primary gwl of most rr:=?.zxh shldies is the identtGcation of the rebticrishtp betrreen a” ‘~expmure” and an outcome of interest. The exposure may be a treatment or intewentton !buch ds fezkl monitoring, tocolysk, or specialized prenaiai care prcgmmsl or a rkk factor (such as parity or past “se of oml:ontmceptives). There are ma?y ways to study aswdations be-
MS.
and Leah L. Albert, CNM.MT-I
hveen exposures and cutcomes; 5ome
stronger
studydesignsare than othzrs in their ability to identify a connection between cause and effect. Causality. however. can rarely be determined on t”s bask oi a mcgle study; it k a cumulative process. Multiple studies conducted with dtfierent group” of subjects should build support foi a consistent relationship between an exposure and an outcome that holds across ?ason. place. and time. This
have Saws in d&n. data callerdon. o* ar.?@k that produce erraneoLE (or biased1 findings. The strongest suppo* for causal inference comes from experimental studies or randomized ‘&a&. Th.eseare studies where subjects who are alike in many ways are m~doml~ assigned by Be researchers to P,X of two groups. One group recewrs an ex@mental treati& or expczuc xd ffie other group does not The P‘OUPS
might be dlffera~t from those who do not(they might besickerormore motivated). Women who chwse midzifey care In out-of-hospital birth centen may have different attitudes, life-styles.or h&h etalusfrom women who chows is hospitel care from a ~
PatriciaAhins Murphy,
CNM,
CG;rical practice is often based on the r&sutk of research. As a wsvlt, the abGity to evaluate a research report nittcaGy k vital. We warIt to incurcarate into ma&e thae Gndin~~sthat
selles of columns. we will review plinci& of researrh metbc&log,~ as they apply to the ec;l!uation of published studies; we begin with a discussion cat randomized trials. The primary gwl of most rr:=?.zxh shldies is the identtGcation of the rebticrishtp betrreen a” ‘~expmure” and an outcome of interest. The exposure may be a treatment or intewentton !buch ds fezkl monitoring, tocolysk, or specialized prenaiai care prcgmmsl or a rkk factor (such as parity or past “se of oml:ontmceptives). There are ma?y ways to study aswdations be-
MS.
and Leah L. Albert, CNM.MT-I
hveen exposures and cutcomes; 5ome
stronger
studydesignsare than othzrs in their ability to identify a connection between cause and effect. Causality. however. can rarely be determined on t”s bask oi a mcgle study; it k a cumulative process. Multiple studies conducted with dtfierent group” of subjects should build support foi a consistent relationship between an exposure and an outcome that holds across ?ason. place. and time. This
have Saws in d&n. data callerdon. o* ar.?@k that produce erraneoLE (or biased1 findings. The strongest suppo* for causal inference comes from experimental studies or randomized ‘&a&. Th.eseare studies where subjects who are alike in many ways are m~doml~ assigned by Be researchers to P,X of two groups. One group recewrs an ex@mental treati& or expczuc xd ffie other group does not The P‘OUPS
might be dlffera~t from those who do not(they might besickerormore motivated). Women who chwse midzifey care In out-of-hospital birth centen may have different attitudes, life-styles.or h&h etalusfrom women who chows is hospitel care from a ~
