U3L7

Question 1

deviation and standard deviation

Answer 1

Deviation - the difference between an individual value, x in a set of data and the mean of the data.

Population deviation = x - μ (x minus population average)
Sample deviation = x - xbar (x minus sample average)
Ex. finding the difference between your test mark and the test mark average.
= x - μ
= 80 - 75
= 5

Standard deviation - calculates the average distance each value in the data set is from the mean. This is the most common measure of spread.

The smaller the standard deviation, the more the data is clustered around the mean while the larger standard deviation, the less the data clusters around the mean.

Question 2

what is spread

Answer 2

(Things that vary from the centre and how far away they are.)

Data far away from the middle are called spread out and when they are closer to the middle they are clustered.

The measures of spread/dispersion of a data set are quantities that indicated how closely a set of data clusters around its centre.

Question 3

variance

Answer 3

Variance - can be found by squaring the standard deviation

Variance = σ2