Info 2040 Foundation of Quantitative Analysis Week 2-1

Class Activities Think of a question that lead you to collecting a data set (comprising of data and cases) Eg. What types of telecommunication operators do students in info 2040 subscribed to? Or what are the weights of the students in this class? Create a data set (a minimum of 50 cases) in the Excel spreadsheet Arrange them as data and cases You may find your data in the internet – describe what the data is about, or for what purpose

Measurement The form in which our data represented What do we normally measure? How do we measure What kind of measurements can you find out there? Why do we measure? Most of the time we measure variables What is a variable?

Measurement and Variable Measurement – the use of any rule to assign numbers to cases so as to represent the presence or absence or quantity of some attribute possessed by each case Variable – an attribute or characteristic that varies from one case to the next

Rules in Measuring Very important Depend on what is being measured More than one way to measure an attribute Sometimes called “scale” or “level” or measurement Will determine how we choose the statistical tools

Scale of Measurement Nominal Ordinal Interval Ratio

Nominal Scale The lowest level of measurement Describes in terms of quality of each case – “what kind” NOT “how much” Eg. Gender – male or female, Describe presence or absence of an attribute – eg. Yes or NO When assigned numbers, the difference has no mathematical value How do we use statistics to describe data in this category?

Ordinal Scale Involves assigning numbers to cases Conveys quantitative information about cases Eg. Strongly agree = 1, Agree = 2, Somewhat agree = 3, Disagree = 4, Strongly disagree = 5 1 is < 2, 3 is > 2 2 – 1 ≠ 3 -2 (the different has no mathematical value)

Interval Scale Scores on the scale variable determined by the number of fixed-sized units No absolute 0 in the variable attribute Arbitrary 0 point – 0 does not means complete absence of attribute 0 represents low quantity The different can be mathematically manipulated – 2 -1 = 3 – 2 = 1 What are other examples of variables measured using interval scale?

Ratio Scale Highest, most flexible level of measurement Data available themselves to all of most powerful statistical procedures Similar to interval scale EXCEPT 0 means 0 What are the example of variables measured using ratio scale?

Assignment 2 In continuation with the data set earlier, Complete the data sheet with at least 50 cases and at least 4 variables that are measured with nominal, ordinal, interval, and ratio scale.