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Chapter 1Statistics: The Art and Science of
Learning from Data
Learn ….
What Statistics Is
Why Statistics Is Important
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Chapter 1
Learn…
How Data is Collected
How Data is Used to Make
Predictions
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Health Study
Does a low-carbohydrate diet result in significant weight loss?
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Market Analysis
Are people more likely to stop at a Starbucks if they’ve seen a recent TV advertisement for their coffee?
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Heart Health
Does regular aspirin intake reduce deaths from heart attacks?
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Cancer Research
Are smokers more likely than non-smokers to develop lung cancer?
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To search for answers to these questions, we…
Design experiments
Conduct surveys
Gather data
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Statistics is the art and science of:
Designing studies Analyzing data Translating data into knowledge and
understanding of the world
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Example from the National Opinion Center at the University of Chicago:
General Social Survey (GSS) provides data about the American public
Survey of about 2000 adult Americans
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Design
How to conduct the experiment
How to select the people for the survey
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Description
Summarize the raw data
Present the data in a useful format
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Example from GSS: On a typical day, about how many hours do you personally watch television?
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What percentage of the people surveyed reported watching 0 hours of TV a day?
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Example: Harvard Medical School study of Aspirin and Heart attacks
Study participants were divided into two groups• Group 1: assigned to take aspirin
• Group 2: assigned to take a placebo
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Example: Harvard Medical School study of Aspirin and Heart attacks
Results: the percentage of each group that had heart attacks during the study:
0.9% for those taking aspirin 1.7% for those taking placebo
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Example: Harvard Medical School study of Aspirin and Heart attacks
Can you conclude that it is beneficial for people to take aspiring regularly?
Example: Harvard Medical School study of Aspirin and Heart attacks
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Subjects
The entities that we measure in a study
Subjects could be individuals, schools, countries, days,…
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Population and Sample
Population: All subjects of interest
Sample: Subset of the population for whom we have data
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Example Format
• Picture the Scenario
• Question to Explore
• Think it Through
• Insight
• Practice the concept
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Example: The Sample and the Population for an Exit Poll
In California in 2003, a special election was held to consider whether Governor Gray Davis should be recalled from office.
An exit poll sampled 3160 of the 8 million people who voted.
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What’s the sample and the
population for this exit poll?
The population was the 8 million people who voted in the election.
The sample was the 3160 voters who were interviewed in the exit poll.
Example: The Sample and the Population for an Exit PollExample: The Sample and the Population for an Exit Poll
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Descriptive Statistics
Methods for summarizing data
Summaries usually consist of graphs and numerical summaries of the data
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Inference
Methods of making decisions or predictions about a populations based on sample information.
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Parameter and Statistic
A parameter is a numerical summary of the population
A statistic is a numerical summary of a sample taken from the population
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Randomness
Simple Random Sampling: each subject in the population has the same chance of being included in that sample
Randomness is crucial to experimentation
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Variability
Measurements vary from person to person
Measurements vary from sample to sample
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a. To describe whether a sample has more females or males.
b. To reduce a data file to easily understood summaries.
c. To make predictions about populations using sample data.
d. To predict the sample data we will get when we know the population.
Inferential Statistics are used: