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Raymond Martin [email protected]. Lecture 6 – Measurement Data are: – pieces of observable...

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Raymond Martin [email protected]. jm
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Page 1: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Raymond Martin

[email protected]

Page 2: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.
Page 3: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement

Data are: – pieces of observable information – limited by measurement

Measurement is:– limiting the data

          

Page 4: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Two types of measurement – Substantial measurement e.g. area

measurement of observable information (variables)

– Insubstantial measurement

Exists only as concepts (opinions, ideas, feelings)

e.g. status

          

Page 5: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

The process of formulating and clarifying concepts into measurable variables is called conceptualisation.– e.g. The concept status can be linked to ownership

of property

Operationalisation develops an expression of what a concept means using operational definitions.– e.g. Upper class means owns home and lower class

means rents home.         

Page 6: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

A constant is a characteristic that is the same for all subjects under study

while…

a variable is a characteristic that takes on different values for subjects under study.        

Page 7: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Identify the constants and the variables

Page 8: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

An Independent variable influences while a Dependent variable is influenced

Page 9: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

A variable may be continuous or discrete

Continuous

• Age, height, time

Discrete

• Gender, book type

Page 10: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

There are four categories or scales of measurement. These are:– nominal– ordinal– interval scale– ratio scale

Page 11: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Nominal– lowest scale – limits data to categories only– no indication of rank or value

e.g. gender, colour

Page 12: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

0

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Black White Brown Purple

Page 13: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Ordinal– limits data to categories

– indicates order

– interval has no meaning

e.g. place in a race (first, second, third)

skill level (unskilled, semi-skilled and skilled)

Page 14: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

0

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1st Qtr 2nd Qtr 3rd Qtr 4th Qtr

Page 15: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Interval Scale– limits data to categories – indicates order – interval has meaning– No true zero

e.g. Celcius scale, IQ, Rating scale

Page 16: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

0

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0 10 20 30 40 50

Temperature

Exp

ansi

on (

%)

Page 17: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Ratio Scale– limits data to categories – indicates order – interval has meaning– true zero

e.g. age, length

Page 18: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

0102030405060708090

100

10 20 30 40

Age

Hei

ght

Page 19: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Validity– accuracy of measurement

Reliability– repeatability of measurement

Page 20: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Validity– Internal (isolation of factors)– External (sampling)

Reliability– Internal (instrument, observers)– External (repeatability by other researchers)

(clear and detailed methodology)

Page 21: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’dA researcher conducts an experiment to compare the durability of a new construction method with that of the traditional construction method.

A one-mile strip of road in a remote area of Manchester is selected and divided into two sections. Construction following one design is done in one section while construction following the other design is done in the other section.

Weekly inspections are made and measurements taken of deterioration of the surface. Two assistants work on the project. One collects data from one section while the other collects data from the other section.

 

Page 22: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Accurate, Precise Valid, Reliable

Page 23: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Inaccurate, Precise

Invalid, Reliable

Page 24: Raymond Martin rmartin@utech.edu.jm. Lecture 6 – Measurement Data are: – pieces of observable information –limited by measurement Measurement is: –limiting.

Lecture 6 – Measurement Cont’d

Inaccurate, Imprecise

Invalid, unreliable


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