Week 2- Quartiles, variance, SD & skewness

Question 1

Define Standard deviation

Answer 1

A measure of variability that describes an average distance of every score from the mean.

Question 2

Define Lower quartile

Answer 2

Median of lower half of ordered data

Question 3

Define Quartile

Answer 3

One of four equal groups each containing a quarter of a statistical population.
The Quartiles, Q1, Q2 and Q3 split the data into 4 parts, with 25% of the information in each

Question 4

Define Interquartile range

Answer 4

The difference between the upper and lower quartiles (Q3 - Q1)

Question 5

Define Variance

Answer 5

A measure of spread within a distribution (the square of the standard deviation).

Question 6

Define Skew

Answer 6

measure of the asymmetry of a probability distribution

Question 7

Define Upper quartile

Answer 7

Median of upper half of ordered data

Question 8

What is a box and whisker plot

Answer 8

used to display information about the range, the median and the quartiles.

Question 9

Define outlier

Answer 9

an extreme value that lies outside the overall pattern of the data
An outlier is any value which is,
greater than the upper quartile + 1.5 x interquartile range
or
less than the lower quartile -1.5 x interquartile range

Question 10

some data are collected. the lower quartile is 46 and the upper quartile is 68. work out weather the following are outliers.
a 7
b 88
c 105

Answer 10

a is an outlier
b is not an outlier
c is an outlier