Contents
What does the Pnorm function do in R?
pnorm is the R function that calculates the c. d. f. where X is normal.
What does the code Pnorm 2 calculate?
pnorm calculates cumulative distribution function of normal distribution, i.e. where μ is mean and σ is standard deviation. As noted by dsaxton to calculate the probabilities for normally distributed random variable X you need only to know μ and σ parameters and apply the function.
What Pnorm gives?
The pnorm function gives the Cumulative Distribution Function (CDF) of the Normal distribution in R, which is the probability that the variable X takes a value lower or equal to x.
What is the syntax of the function dnorm?
The function dnorm returns the value of the probability density function (pdf) of the normal distribution given a certain random variable x, a population mean μ and population standard deviation σ. The syntax for using dnorm is as follows:
How to use pnorm and qnorm in R?
We then can apply the pnorm function as follows: Based on the plot function, we can illustrate the output of the pnorm function: Figure 2: Probability of Normally Distributed Random Number. R provides the qnorm command to get the quantile function (i.e. the inverse of the CDF that was shown in Example 2).
How does the dnorm function return the probability distribution?
The dnorm function returns the probability distribution for a given mean and standard deviation. In order to apply the dnorm function, we first need to specify all values for which we want to return the probability:
Which is the inverse of the CDF in pnorm?
To remember that pnorm does not provide the PDF but the CDF, just imagine that the function carries a p in its name such that pnorm is lexicographically close to qnorm, which provides the inverse of the CDF. The quantile function is simply the inverse of the cumulative density function (iCDF).