Reading the data

Read the data dictionary for this simulated dataset to familiarise yourself with the variables.

Information: the data dictionary

The names of all other variables end in either .7 or .11 (depending whether they were measured at the age 7 clinic or the age 11 clinic)

male codes sex: 1=male, 0=female

age.yrs and age.yrs are the age (in decimal years) on the day of the clinic at age 7 or 11

ht is height in cm

ht.sit is sitting height in cm

ws is waist circumference in cm

hp is waist circumference in cm

wt is weight in Kg

sbp is systolic blood pressure (the top of the blood pressure fluctuation) measured (as is conventional) in mm of Hg (mercury)

dbp is diastolic blood pressure (the bottom of the blood pressure fluctuation) measured (as is conventional) in mm of Hg (mercury)

pulse is pulse rate measured in beats per minute

BMI is body mass index derived as wt/(ht/100)² The height variable is divided by 100 to express it in metres rather than centimeters

set the working directory using setwd and read the dataset into R and assign it the variable sim.alspac using the read.csv function
Look up the colnames function in the help file and apply it to sim.alspac to list all the column headings in the data.
Look up the dim function in the help file and apply it to to sim.alspac to get the dimensions of the dataset. Number of columns is the number of variables, number of rows is the number of participants.

Subsetting and assigning data

table( )

ftable( )

summary()

hist()

boxplot()

signif(x, digits = 6)

# set how many significant figures using digits =

or use

format(round(x, 2), nsmall = 2)

# for two d.p

text(70,12, labels=paste("y=", RegM11$coefficients[2], "+", RegM11$coefficients[1]), col="orange")