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Exercice de révision de la séance 1

 
http://forge.info.univ-angers.fr/~gh/wstat/Introduction_R/revision1.php
 

          

          non su

Essayer de lire les données DIABETE pour en faire un data.frame avec comme seules colonnes id glyhb age gender height weight waist hip que l'on viendra convertir en unités métriques. Il s'agit du jeu de données diabete extrait des datasets du professeur F. Harrell fournies pour son livre Regression Modeling Strategies. On se méfiera des nombreuses données manquantes.

On construira ensuite une variable "diabète diagnostiqué" suite à la lecture de l'abstract pubmed/9258308. (extrait encadré ci-dessous). Pour cet exercice, on pourra donc ignorer les variables chol, stab.hlu, hdl, ratio, location, frame, bp.1s, bp.1d et time.ppn puis ajouter une variable rapport ceinture/hanches nommée rach.

Remarque : si vous n'arrivez pas à lire le fichier Excel, vous pouvez vous rabattre sur le fichier diabete.dar qui a les mêmes données manquantes, repérées par NA. 


     Prevalence of coronary heart disease risk factors among rural blacks: a community-based study
     (diabetes Dataset).
     
     These data are courtesy of Dr John Schorling, Department of Medicine,
     University of Virginia School of Medicine.
     
     The data consist of 19 variables on 403 subjects from 1046 subjects who
     were interviewed in a study to understand the prevalence of obesity, diabetes,
     and other cardiovascular risk factors in central Virginia for African Americans.
     According to Dr John Hong, Diabetes Mellitus Type II (adult onset diabetes) is
     associated most strongly with obesity. The waist/hip ratio may be a predictor
     in diabetes and heart disease. DM II is also agssociated with hypertension
     - they may both be part of "Syndrome X". The 403 subjects were the ones who
     were actually screened for diabetes. Glycosolated hemoglobin > 7.0 is usually
     taken as a positive diagnosis of diabetes.
     
     Background. Coronary heart disease (CHD) remains the most common cause of
     death among blacks, and the difference in CHD mortality between blacks
     and whites is growing. This trend may be due in part to higher rates of
     CHD risk factors among blacks. This study was done to determine the
     prevalence of CHD risk factors among a population-based sample of 403
     rural blacks in Virginia.
     
     Methods. Community-based screening evaluations included the
     determination of exercise and smoking habits, blood pressure,
     height, weight, total and high-density lipoprotein (HDL)
     cholesterol, and glycosylated hemoglobin.
     
     (C) 1997 Southern Medical Association

Il faudra peut être utiliser les fonctions suivantes

                read.xls()       du package       gdata
                summary()       du package       base
                <-       du package       base
                [       du package       base
                get()       du package       base
                na.omit()       du package       stats
                attach()       du package       base
                detach()       du package       base
                ifelse()       du package       base
                levels()       du package       base

 

 

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