R中的密度分布

Question

An assignment has tasked us with creating a series of variables: normal1, normal2, normal3, chiSquared1 and 2, t, and F. They are defined as follows:

library(tibble)
Normal.Frame <- data_frame(normal1 = rnorm(5000, 0, 1), 
    normal2 = rnorm(5000, 0, 1), 
    normal3 = rnorm(5000, 0, 1), 
    chiSquared1 = normal1^2, 
    chiSquared2 = normal2^2, 
    F = sum(chiSquared1/chiSquared2), 
    t = sum(normal3/sqrt(chiSquared1 )))

We then have to make histograms of the distributions for normal1, chiSquared1 and 2, t, and F, which is simple enough for normal1 and the chiSquared variables, but when I try to plot F and t, the plot space is blank.

Our lecturer recommended limiting the range of F to 0-10, and t to -5 to 5. To do this, I use:

HistT <- hist(Normal.Frame$t, xlim = c(-5, 5))

HistF <- hist(Normal.Frame$F, xlim = c(0, 10))

Like I mentioned, this yields blank plots.

Answer 1

Your t and F are defined as sums; they will be single values. If those values are outside your range, the histogram will be empty. If you remove the sum() function you should get the desired results.