Measures of dispersion (lecture 3)

LECTURE 3
MEASURES OF DISPERSION
Temur Makhkamov
Indira Khadjieva
QM Module Leaders
tmakhkamov@wiut.uz
i.khadjieva@wiut.uz
Room: IB

Lecture outline:
compute and interpret the (interquartile) range
compute and interpret the variance

Untabulated data.

According to Transfermarkt.ru transfer price of some Uzbek National

Range
Range = Max value – Min value
Range = € 7,000,000 -

Interquartile range

Interquartile range
IQR = Q3 – Q1 = €2.8mln– €0.6mln= €2.2mln
Visually:
€0.5mln €0.55

Untabulated data

The weekly salaries for the sample of six players of

Standard deviation – Untabulated (1)

Compute the mean
Calculate the difference from

Standard deviation – Untabulated (2)

Standard deviation – Untabulated (3)

Empirical rule: For a normal distribution:
Within one

Tabulated - ungrouped data

The number of Rolton (noodle) sold per day

Range

Range = Max value – Min value
Range = 16 - 10

Standard deviation formulae
Scary formula?
It is hard to solve?
Let’s solve it

Standard deviation – 1st method (1)

Standard deviation – 1st method (2)

Standard deviation – 2nd method
Homework:
Try to solve it at home

Tabulated – grouped data

The amount spent on food by 50 people

Range

Range = Max value – Min value
Range = £50 - £0

Standard deviation – 2nd method (1)

Standard deviation – 2nd method (2)

Standard deviation – 1st method
Homework:
Try to solve it at home

Confidence interval

The 95% confidence interval is a range of values that

Concluding remarks:
Today, you learnt:
Use the quantitative methods to find the spread