연구방법론의토대The Foundations of Research Methods

대학원의료관리학특론강의2013. 11. 21.

서울의대의료관리학교실도영경

All figures used herein are from class reading materials: Trochim and Gilson.

새로운분야에발을디딜때: 의학도, 의학연구자의경우

• 의학개론– 역사– 철학– 윤리

• 임상총론– SOAP Notes– 면담기술

• 의학연구방법론– 의학과과학– 의학에서의인과관계– 연구의분류

다른분야의경우

• (범죄)수사학총론• 연기학총론• 오리고기학총론• 풍수총론• 죽음학총론• 게임개발총론• …

(의료관리)연구총론에대한이해가부족할때흔히나타나는증상또는불편한진실

(약간의과장을덧붙여)

Title: “Factors associated with …”

• 이런제목의연구가일반적으로나쁘다고말하는것이아님

• 문제는연구의목적과성격을분명히하지않고무작정통계패키지를돌리고통계적유의성보고로연구를대체하는경향임

• 실제사례– 학회발표전통계상담실에온모과 R4

I. Introduction

• 연구의동기가불명확함:– “국내의관련연구는부족한실정이다”

• 연구문제가명확하지않음– 문제의크기기술로대체, wandering

• 연구의목적이불명확함– “기초자료를제공하고자한다”

• 개념적틀과이론을거추장스럽게생각함– 개념적틀은비슷한내용을다룬좋은논문에서그럴싸한것을뽑아이미수행된자신의분석을포장하는것이라고생각함

– 이론은이론일뿐이라생각함– 가설은자신의 (심오한/다면적인) 연구를지나치게단순화시켜버린다고생각함

II. Methods

• “연구방법=통계분석”이라고생각하는경향• 왜 bivariate analysis를해야하는지설명하지못함

• p-value를 Table 1에서제시해야할까, 아닐까고민함

• 왜multiple logistic regression을굳이하는지설명하지못함

• 통제, 보정이무슨말인지정확히이해하지못하고분석에적용하지못함

III. Results

• x1은유의• x2는유의하지않음• …• xn은유의함

IV. Discussion

• 이연구에서통계적으로유의한변수는 xk임• 다른연구에서는 xk가유의하지않았으나이연구에서는다른결과(p=0.045)라서흥미로움.

• 김(2012)과이(2013) 연구에서는 xa, xb 등이유의하였음.

• xk(예: 사회경제적특성등)이 Y문제해결에중요함• xk 가인과적으로관련되어있지않을수도있다는제한점

• xk 외에다른요인을보려는후속연구필요• 정책적노력이 xk 해결에집중되어야함

왜이런제목이 (의료관리)연구에서팽배할까

• 연구훈련부족; 따라하기• 예방의학에서의료관리학이발전해온역사적배경– 역학

• 질병(Y)의위험요인(x1, x2, x3, …)이무엇인지잘모름• xk와 Y의관련성은그자체로의미가있는경우가많음(tumor marker, indicator)

– 보건통계학• 자료와통계방법론이일차적, 이론이출발점이아님• Model building primarily by data and fitness

이런제목의연구가가질수있는문제점

• 연구의초점이모호함• 일반적지식(generalizable knowledge) 창출가능성이낮음– 시공간적배경– 자료– 변수정의– 공변인(covariates)

• 연구자가아닌 SAS/Stata/SPSS가연구를함– 주객전도

• 결론으로는

Kitchen sink

Kitchen sink regression• A kitchen sink regression is an informal and usually pejorative term

for a regression analysis which uses a long list of possible independent variables to attempt to explain variance in a dependent variable. In economics, psychology, and other social sciences, regression analysis is typically used deductively to test hypotheses, but a kitchen sink regression does not follow this norm. Instead, the analyst throws "everything and the kitchen sink" into the regression in hopes of finding some interesting statistical pattern. The results of this type of regression may be interpreted inductively to suggest that the same pattern of relationships between independent and dependent variables will be found in other data, which can lead to hasty generalizations.

• The kitchen sink regression is an example of the practice of data dredging.

Source: Wikipedia

Dredging: 준설, 물밑바닥을훑다

Unthinkable in social science research

• Stepwise regression– Forward selection– Backward selection– Bidirectional elimination

cf. Hierarchical models

Source: Wikipedia

이런방식의연구가의미있는경우

• Y에영향을미치는요인이전반적으로잘알려져있지않은경우– 연구가많이되지않았거나아직병인을모르는경우

– 관련요인에대한지식이극히부족한경우: GWAS

• xk가 Y와관련되어있다는것을아는것만으로도가치있는경우– Detection (screening)– Monitoring

Biomarker

Marker Onset,

Recurrence,Progression

Disease

의료관리학에서이런연구의의미

• 다학제적(multidisciplinary) 성격이므로구체적연구문제에따라다름

• 그러나앞서기준을적용해보면,– Y(cost, quality, access)가잘알려져있지않은것?– Program, Policy, SEP 등이 Y에어떤영향을미칠지우리에게이론이없는가?

• 의료관리학방법론은통계학적지식과함께“이론적” 정교함을상당히필요로함

예시: JCI 인증과의료의질

• 문제(problem): JCI 인증의심스러운질향상효과

• H1 (=Ha): JCI 인증을받은기관이그렇지않은기관은의료의질이다르다.

• Testable?• By testing this H, what would we know?

– JCI 인증은질향상에유용한도구이다?– JCI 인증을요구해야한다?– JCI 인증이별필요없다?

Types of Questions

• Descriptive.• Relational.• Causal.

• Cumulative?: Yes!• 연구의가치?: Not necessarily

Multiple research purposes

Descriptive/Relational

• Wennberg J, Gittelsohn A. Small area variations in health care delivery. Science. 1973;182:1102-1108.

• Global Burden of Disease studies• Warren CW, Jones NR, Eriksen MP, Asma S; Global

Tobacco Surveillance System (GTSS) collaborative group. Patterns of global tobacco use in young people and implications for future chronic disease burden in adults. Lancet. 2006 Mar 4;367(9512):749-53.

Causal (1)• Grabowski DC, Feng Z, Hirth R, Rahman M, Mor V.

Effect of nursing home ownership on the quality of post-acute care: an instrumental variables approach. J Health Econ. 2013 Jan;32(1):12-21.

• Mukamel DB, Weimer DL, Harrington C, Spector WD, Ladd H, Li Y. The effect of state regulatory stringency on nursing home quality. Health Serv Res. 2012 Oct;47(5):1791-813.

• Werner RM, Konetzka RT, Polsky D. The effect of pay-for-performance in nursing homes: evidence from state Medicaid programs. Health Serv Res. 2013 Aug;48(4):1393-414.

Causal (2)

• Effect of ACO on quality• Effect of PCMH on quality

Both used difference-in-differences

Hourglass and diamond

Level of detail in descriptionResearch process

Deductive reasoning(연역적추론)

Inductive reasoning(귀납적추론)

The major realms and components of research

The validity questions

Combine and compare the two figures

Discussion