# STAT151 Lecture Notes - Lecture 2: Frequency Distribution, Contingency Table, Descriptive Statistics

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6 Feb 2016
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January 12, 2016
Chapter 2: Displaying and Describing Categorical Data
We will study the categorical variables using descriptive statistics in this chapter.
In this chapter we will talk about:
Frequency Tables,
Bar Chart, Pareto Diagram, and Segmented Bar Chart,
Pie Chart,
Contingency Tables
Example 1:
To study marks in Stat 151 classes, we selected three classes D1, R1 and X1 from all Stat 151 classes offered in one academic year in
U of A. The following information is obtained for all students in these three classes:
What: ID, Class, Marks for Midterm, Homework, Lab Assignments, Term work (30% Midterm, 10% Homework and 10% Lab
Assignments), Final Exam, Final Mark (50% Term work and 50% Final Exam), and Letter Grades.
Who: Students in Stat 151 classes (D1, R1, and X1)
Where: U of A
Why: Study marks in Stat 151 classes
Categorical Variables:
oNominal: Classes (D1, R1 and X1)
oOrdinal: Letter Grades (A, B, C, D and F)
oIdentifier variable: ID
Quantitative variables:
oDiscrete: Midterm, Final Exam
oContinuous: Homework, Lab Assignments, Term Work and Final Mark (If not rounded at the end)
Which of the following statements is TRUE?
(a) We can make causal (causeandeffect) inferences, since this is an experiment
(b) We cannot make causal inferences, since the sample size is not large enough
(c) We can make causal inferences, since this is an observational study
(d) We cannot make causal inferences, since this is an observational study
(e) We can make causal inferences, since we have random sampling
What is the name of this sample?
(a) Simple random sample
(b) Systematic sample
(c) Stratified sample
(d) Cluster sample
(e) Census
The three rules of data analysis are: draw a picture, draw a picture, and draw a picture.
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