CHAPTER 1 STATISTICS

1 / 19

CHAPTER 1 STATISTICS - PowerPoint PPT Presentation

CHAPTER 1 STATISTICS. Statistics is a way of reasoning, along with a collection of tools and methods, designed to help us understand the world. READ THE BOOK. Think Show Tell For Example Step-by-Step What can go wrong* What have we learned?. CHAPTER 2 DATA.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about ' CHAPTER 1 STATISTICS' - tieve

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

CHAPTER 1STATISTICS

Statistics is a way of reasoning, along with a collection of tools and methods, designed to help us understand the world

• Think
• Show
• Tell
• For Example
• Step-by-Step
• What can go wrong*
• What have we learned?
CHAPTER 2DATA
• Information together with its context
• Numerical
• Names
• Labels
• Five W’s
• Who, What, When, Where, Why
• How
WHO
• Respondents: Individuals who answer a survey
• Subjects or Participants: People on whom we experiment. (Experimental Units)
• Records or Cases: Rows in a database or data table. Individuals about whom or about which, we have the data.
WHAT
• Variables
• Characteristics recorded about each individual. These are usually columns in a data table, and they should have a name that identifies what has been measured.
• Categorical (or Qualitative)
• Quantitative (Numerical values with measurement units)
• Ordinal
…more W’s
• Where and When?
• Country? Year?
• How?
• How the data was collected?
• Why?
• Reason for the study
Exercise
• Investments. According to an article in Fortune (Dec.28, 1992), 401(K) plans permit employees to shift part of their before-tax salaries into investments such as mutual funds. Employers typically match 50% of the employees’ contribution up to about 6% of salary. One company, concerned with what it believed was a low employee participation rate in its 401(k) plan, sampled 30 other companies with similar plans and asked for their 401(k) participation rates.
Identify the W’s
• Who ?
• 30 Companies
• What ?
• Participation Rates
• Quantitative (Units : Percent)
• When ?
• Sometime after 1992
Identify the W’s (cont.)
• Where ?
• USA
• Why ?
• The company was concerned with its participation rate compared with other companies
• How ?
• Companies were sampled using an unspecified method
Exercise
• Flowers. In a study appearing in the journal Science a research team reports that plants in southern England are flowering earlier in the spring. Records of the first flowering dates for 385 species over a period of 47 years indicate that flowering has advanced an average of 15 days per decade, an indication of climate warming according to the authors.
Identify the W’s
• Who ?
• 385 species of flowers over 47 years
• What ?
• First flowering date
• Quantitative (Units : days)
• When ?
• Not specified
Identify the W’s (cont.)
• Where ?
• Southern England
• Why ?
• Researchers associate this behavior with climate warming
• How ?
• Observation. ( Method not specified)
Chapter 3. Displaying and Describing Categorical Data
• Make a picture
• First Make piles
• Organize the counts by categories in a frequency table (counts) or a relative frequency table (percentages)
• Both types of tables describe the distribution of the categorical variable because they name the possible categories and tell how frequently each occurs
The Area Principle
• The area occupied by a part of the graph. It should correspond to the magnitude of the value it represents
Bar Charts
• A bar chart displays the distribution of a categorical variable, showing the counts for each category next to each other for easy comparison.
Pie Charts
• Relative proportion (percentages instead of counts).
• Pie charts show the whole group of cases as a circle, each of the pieces has a size proportional to the fraction of the whole in each category.
Contingency Tables
• Two categorical variables
Marginal and Conditional distributions
• Marginal Distribution
• Distribution of either variable alone (at the margin of the table)
• Conditional Distribution
• A distribution in one variable for only those individuals satisfying some condition on another variable.
• Note : If the distribution of one variable is the same for all categories of another we say that the variables are independent.
Exercises
• Step-by-Step page 31
• What can go wrong
• Check the charts on pages 34