25 - BUAD 310: Applied Business Statistics August 25, 2010...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
August 25, 2010 BUAD 310: Applied Business Statistics 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Outline for Today Descriptive statistics Variables and their distributions Finding the center Measuring the spread Relationship between variables 2
Background image of page 2
Data Consists of values of some variables measured or observed for some individuals . E.g., the data set from the class survey (13 variables for the students in our class). Variable is a characteristic of an individual. Qualitative or Categorical : places an individual into one of several groups or categories (finitely many possible) Quantitative : measurements represent quantities, e.g. “how many” (infinitely many possible), could be discrete or continuous 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Scales of Measurement Quantitative Ratio variable, almost all quantitative variables are ratio variables Ratios meaningful, inherently defined zero (e.g., salary, weight, distance) Interval variable, very few quantitative variables are interval variables Ratios not meaningful, no inherently defined zero (e.g., temperature) Categorical Ordinal variable Meaningful ordering or ranking of categories (e.g., class) Nominative variable No meaningful ordering or ranking of categories (e.g., gender, color) 4 R a t i o ( a l m o s t a l l ) I n t e r v a l ( v e r y f e w ) Q u a n t i t a t i v e O r d i n a l N o m i n a t i v e Q u a l i t a t i v e ( C a t e g o r i c a l ) D a t a
Background image of page 4
Data Analysis Initial examination of the data is called Exploratory Data Analysis (EDA). Strategy for EDA: Begin by examining each variable and then move on to the study of relationships At each stage start with graphs and then add numerical summaries 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Distribution of a Variable Describes what possible values the variable takes and how frequently it takes those values. We describe the overall pattern of a distribution by its shape, center, and spread. There are many ways to describe and display distributions. Graphs Word descriptions Numerical measures 6
Background image of page 6
Describing Categorical Data Describing Categorical Data 7 Motivating Example: Everyday, more than 100 million shoppers visit amazon.com, either by typing amazon.com or by clicking an ad. Which hosts send the most visitors to Amazon’s Web site? Data set consists of 188,996 visits Host is a categorical variable To answer this question we must describe the variation in Host
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Data Table Frequency and Relative Frequency Tables The distribution of a categorical variable is a list of values with its associated count (frequency) A frequency table summarizes the distribution of a categorical variable A relative frequency table shows the proportion (or percentage) in each category 8
Background image of page 8
9 Looking At Data
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10 Charts of Categorical Data Bar Charts and Pie Charts Unless you need to know exact counts, charts are better than tables for summarizing more than five categories The two most common displays of a categorical variable are a bar chart and a pie chart
Background image of page 10
11 Charts of Categorical Data The Bar Chart Uses horizontal or vertical bars to show the
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/30/2010 for the course BUAD 310 at USC.

Page1 / 72

25 - BUAD 310: Applied Business Statistics August 25, 2010...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online