Question

In R, compute the mean and standard deviation for at least three numerical data columns. You will need to use read.csv to read your data file into an R data frame. Post your code on GitHub, and post the means and standard deviations on your webpage.

Answer 1

SOl:

url <- "http://rstatistics.net/wp-content/uploads/2015/09/ozone.csv"  
ozonedt <- read.csv(url)
dim(ozonedt)
names(ozonedt)

there were 366 rows and 13 columns.

column names are:

[1] "Month" "Day_of_month" "Day_of_week" "ozone_reading"   
[5] "pressure_height" "Wind_speed" "Humidity" "Temperature_Sandburg"
[9] "Temperature_ElMonte" "Inversion_base_height" "Pressure_gradient" "Inversion_temperature"
[13] "Visibility"

To get mean and standard deviation for at least three numerical data columns

Rcode is

mean(ozonedt$Wind_speed,na.rm=TRUE)
mean(ozonedt$Humidity,na.rm=TRUE)
mean(ozonedt$Temperature_Sandburg,na.rm=TRUE)
sd(ozonedt$Wind_speed,na.rm=TRUE)
sd(ozonedt$Humidity,na.rm=TRUE)
sd(ozonedt$Temperature_Sandburg,na.rm=TRUE)

OUTPUT IS:

> dim(ozonedt)
[1] 366 13
> names(ozonedt)
[1] "Month" "Day_of_month" "Day_of_week" "ozone_reading"   
[5] "pressure_height" "Wind_speed" "Humidity" "Temperature_Sandburg"
[9] "Temperature_ElMonte" "Inversion_base_height" "Pressure_gradient" "Inversion_temperature"
[13] "Visibility"
> head(ozonedt)
Month Day_of_month Day_of_week ozone_reading pressure_height Wind_speed Humidity
1 1 1 4 3.01 5480 8 20
2 1 2 5 3.20 5660 6 NA
3 1 3 6 2.70 5710 4 28
4 1 4 7 5.18 5700 3 37
5 1 5 1 5.34 5760 3 51
6 1 6 2 5.77 5720 4 69
Temperature_Sandburg Temperature_ElMonte Inversion_base_height Pressure_gradient
1 NA NA 5000 -15
2 38 NA NA -14
3 40 NA 2693 -25
4 45 NA 590 -24
5 54 45.32 1450 25
6 35 49.64 1568 15
Inversion_temperature Visibility
1 30.56 200
2 NA 300
3 47.66 250
4 55.04 100
5 57.02 60
6 53.78 60
> mean(ozonedt$ozone_reading,na.rm=TRUE)
[1] 11.51934
> mean(ozonedt$Wind_speed,na.rm=TRUE)
[1] 4.868852
> mean(ozonedt$Humidity,na.rm=TRUE)
[1] 58.47578
> mean(ozonedt$Temperature_Sandburg,na.rm=TRUE)
[1] 61.91484
> sd(ozonedt$Wind_speed,na.rm=TRUE)
[1] 2.116928
> sd(ozonedt$Humidity,na.rm=TRUE)
[1] 19.75923
> sd(ozonedt$Temperature_Sandburg,na.rm=TRUE)
[1] 14.27653