Question

3)Johnson et al (A-16) performed a retrospective review of 50 fetuses that underwent open fetal myelomeningocele closure. The data below shw the gestational age in weeks of the 50 fetuses undergoing the prodecure. 25 25 26 27 29 29 29 30 30 31 32 32 32 33 33 33 33 34 34 34 35 35 35 35 35 35 35 35 35 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 36 37 37

a) construct a stem-and leaf plot for these gestational ages.

b)Based on the Stem- and leaf plot, what one worn would you use to describe the nature of the date?

c)why do you think the stem and leaf plot look the way it does?

d)compute the mean, median, variance, and standard deviation.

Answer 1

(a) From RStudio, we get the following stem and leaf plot.

Code:

> data=c(25, 25, 26, 27, 29, 29, 29, 30, 30, 31, 32, 32, 32, 33, 33, 33, 33, 34, 34, 34, 35, 35, 35, 35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 37, 37)

> stem(data)

(b) From the plot above, we can say the nature of the data is skewed. More specifically, it is negatively skewed.

(c) The reason behind it can be summarised as, the more the gestational ages of the fetuses the more it gets exposed to the risk of fatal myelomeningocele closure.

(d) Mean=33.68

Median=35

Variance=10.30367

standard deviation=3.209934

Code:

> mean(data)
> median(data)

> var(data)

> sqrt(var(data))