1 Descriptive Statistics

Question 1

What is descriptive statistics

Answer 1

Method of organising, summarising and presenting data in a convenient and informative way

Question 2

How would we plot categorical data?

Answer 2

Bar chart

Question 3

How would we plot numerical data? Why?

Answer 3

Histogram
Box plot
To show distribution = shape, centre & variation

Question 4

What would a left skewed and right skewed distribution shape look like?

Answer 4

Left skewed- mean < median - long left tail, mean is on left of peak
Right skewed- mean > median - long right tail, mean is on right if peak

Question 5

How can we describe central tendency?

Answer 5

Mean
Median
Mode

Question 6

What measures do we use for variation?

Answer 6

Range
IQR
Variance
SD
coefficient of variation

Question 7

What is the mean affected by that the median and mode aren’t ?

Answer 7

Outliers

Question 8

How is sample variance calculated?

Answer 8

Average of (deviations) squared from the mean
Squaring eliminates the negatives

Question 9

How is standard deviation calculated?
What are the units?

Answer 9

Square root of sample variance
Same units as the original data

Question 10

What are the different types of data?

Answer 10

Categorical - binary, nominal, ordinal
Quantitative- continuous, discrete

Question 11

What does a right skewed and left skewed box plot look like

Question 12

If the distribution is bell shaped, what is the approximate range of SDs?

Answer 12

RANGE = 6SD for normal distribution curves

Question 13

The highest and lowest value for a bell shaped curve are 8.5 and 4. What is the estimated SD?

Answer 13

0.75
Range=6SD