The diastolic blood pressures (DBP) of a group of young women are Normally distributed with mean 67 mmHg and a standard deviation of 9 mmHg.
I am currently trying to analyze some data and am new to statistics with R.
Following above question , i want to see how to display using R, how the following statement are true or false.
About 95% of the women have a DBP between 58 and 76 mmHg.
About 50% of the women have a DBP of above 67 mmHg.
About 2.5% of the women have DBP below 49 mmHg.
What proportion of young women have a DBP between 58 mmHg and 85 mmHg?
I tried solving it manually . But want to display it using R.
CodePudding user response:
Here is code that illustrates some of these concepts. You can use the dnorm
function inside the stat_function
layer of ggplot2
. I put the mean as 0 and standard deviation as 1, and calculated the z-scores bases on that. In your case, you could change the mean to 67 and sd to 9 and change the vertical lines for the z-scores accordingly. But you don't need to visualize this in R to find the answers. Try to familiarize yourself with the dnorm
, pnorm
, rnorm
family of functions.
ggplot(data.frame(x = c(-4, 4)), aes(x))
stat_function(fun = dnorm,
geom = "area", fill = '#ffe6b7', color = 'black', alpha = 0.5,
args = list(
mean = 0,
sd = 1))
labs(title = "Standard Normal Distribution", subtitle = "Standard Deviations and Z-Scores")
theme(plot.title = element_text(hjust = 0.5, face = "bold"))
theme(plot.subtitle = element_text(hjust = 0.5))
geom_vline(xintercept = 1, linetype = 'dotdash', color = "black")
geom_vline(xintercept = -1, linetype = 'dotdash', color = "black")
geom_vline(xintercept = 2, linetype = 'dotdash', color = "black")
geom_vline(xintercept = -2, linetype = 'dotdash', color = "black")
geom_vline(xintercept = 3, linetype = 'dotdash', color = "black")
geom_vline(xintercept = -3, linetype = 'dotdash', color = "black")
geom_text(aes(x=1, label="\n 1 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))
geom_text(aes(x=2, label="\n 2 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))
geom_text(aes(x=3, label="\n 3 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))
geom_text(aes(x=-1, label="\n-1 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))
geom_text(aes(x=-2, label="\n-2 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))
geom_text(aes(x=-3, label="\n-3 σ", y=0.125), colour="#376795", angle=90, text=element_text(size=11))