Getting confidence intervals

Using confidence intervals allows us to estimate the interval range of unknown parameters in the data. In this recipe, we will teach you methods that can help obtain confidence intervals in R.

Getting ready

Ensure that you installed R on your operating system.

How to do it…

Perform the following steps to obtain confidence intervals:

1. Let's first generate a normal distribution using the rnorm function:

   >set.seed(123)
   >population<- rnorm(1000, mean = 10, sd = 3)
   >plot(dens, col="red", main="A density plot of normal distribution")
   

   

   Figure 1: A density plot of normal distribution

2. Next, we will sample 100 samples out of the population:

   >samp<- sample(population, 100)
   >mean(samp)
   [1] 10.32479
   >sd(samp)
   [1] 3.167692
   

3. At this point, we can obtain the Z-score at a confidence of 99%:

   > 1 - 0.01 / 2
   [1] 0.995
   
   >qnorm(0.995)
   [1] 2.575829
   

4. We can now compute the standard deviation error and estimate the upper and lower bounds of the population mean:

   >...