Reading the data 

• Download the D2K simulated ALSPAC dataset. 

...

• 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

Descriptive / summary stats in R

• contingency table (a summary table of 3+ variables) gender, age, BMI

table( )

ftable( )

• summary stats  mean, min, max and quantiles

summary()

• histogram - to identify  types of distributions of a variable

hist()

• box and whisker plot summarizes graphically the min, max, 25-75 percentiles

boxplot()

Rounding numbers

signif(x, digits = 6)

# set how many significant figures using digits =

or use

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

# for two d.p

Adding text to graphs

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