Reproducible Pitch - BMI Calculator

Nihar Satsangi
10/22/2017

About Body Mass Index (BMI) and the Calculator

  • It is defined as the body mass(kg) divided by the square of the body height(m), and is universally expressed in units of kg/m2.

  • It is an attempt to quantify the amount of tissue mass in an individual, and then categorize that person as underweight, normal weight, overweight, or obese based on that value.

  • Commonly accepted BMI ranges are underweight: under 18.5 kg/m2, normal weight: 18.5 to 25, overweight: 25 to 30, obese: over 30.

  • This BMI calculator computes the BMI of the user and then uses that BMI value to analyse the user's risk category.

What the App Does - Server Calculations: Part 1

Firstly, the user is asked to input the weight(kg) and height(m). When this is done, the server first calculates the BMI through the following function:

bmiValue <- function (w,h) w/h^2

#Let's take an example here, taking w=47(kg) and h=1.5(m)

bmiValue(47,1.5)

[1] 20.88889

What the App Does - Server Calculations: Part 2

Then the server passes the bmi value to the following function to analyse the risk category, the user belongs to:

bmirisk   <- function (bmi) {
  if (!is.na(bmi)) {
    if (bmi < 18.5) "Low Risk category but your weight is in the unhealthy range for your height"
    else if (bmi <= 25.0) "Low Risk category"
    else if (bmi < 30.0) "Moderate Risk category"
    else "High Risk category"
  } else "" 
}
# Taking the same values as before:
bmirisk(bmiValue(47,1.5))   

[1] "Low Risk category"

Thank You