Descriptive statistics

Question 1

What are the three measures of central tendency and What are two levels of dispersion

Answer 1

CT: Mean, Median, Mode

Dispersion: Range and Standard deviation

Question 2

What is the Mean and give a strength and a weakness of using it

Answer 2

Mean – Adding up all data and dividing by the number of data items. Ratio, Interval

Strength – Considers all data values.
Weakness – Significantly skewed by extreme values

Question 3

What is the Mode and give a strength and a weakness of using it

Answer 3

Mode – Most common data item. Only type than can be used for Nominal as it does not need to use numbers.

Strength - Not affected by extreme scores.
Weakness – Not useful is there are several modes.

Question 4

What is the Median and give a strength and a weakness of using it

Answer 4

Median – Middle value in ordered list.

Strength – Not affected by extreme scores.
Weakness – Doesn’t consider exact values of all the data.

Question 5

What is the Range and give a strength and a weakness of using it

Answer 5

Range – Lowest data value minus the highest data value.

Strength - Very quick and easy to calculate
Weakness - SIGNIFICANTLY affected by extreme values

Question 6

Describe how to calculate Standard Deviation (6 steps)

Answer 6

Step 1: Find the overall mean of the data items.
Step 2: Subtract this mean from each data item.

(with these numbers you put the next 3 steps into one equation)

Step 3: Square each deviation.
Step 4: Add the squared deviations.
Step 5: Divide the sum by the number of scores -1

Step 6: Take the square root of the result from Step 5.