L3 - Frequency Distributions

Question 1

What are the steps involved in finding a frequency distribution?

Answer 1

1. Sort data
2. Find Range
3. Decide on what bins you want
4. Calculate mid-bins
5. Count observations and assign to bin (or just use the histogram-maker in Excel

Question 2

What is the difference between a histogram and a frequency polygon?

Answer 2

Histograms look like bar charts and don’t require you pay attention to mid-bins
Frequency polygons look like line graphs and each data point corresponds to a mid-bin

Question 3

In normally distributed data, what proportion of the data lies within 1, 2, 3 std devs. of the mean respectively?

Answer 3

1 = 68.26%, 2 = 95.44%, 3 = 99.74%

Question 4

What are the three main properties of normally distribution?

Answer 4

1. Symmetric
2. Asympototic - The tails of the curve get closer and closer to the horizontal axis, but never touch it
3. Total area beneath the curve = probability of 1 e.g all values fall underneath the curve

Question 5

What is kurtosis?

Answer 5

A measure of how peaked (and to some extent how varied) normally distributed data is

Question 6

What are the three categories of kurtosis?

Answer 6

Leptokurtic
Mesokurtic
Platykurtic