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Chapter 1: Introduction to Statistics

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What is Data?

Where does data come from??????observations, counts, measurements, or responses

Numbers with a context

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There are generally two main sources of data:

Observational Studies Experiments

Experiments occur in a controlled environment and they aim to establish a cause-effect relationship between two variables.

Observational studies occur in a natural environment, and they can never establish a cause-effect relationship. An observational study usually involves taking a sample from the population, measuring some characteristic about that sample , and then using that statistic (measurement) to make assumptions about the entire population. A census is a special kind of observational study that attempts to measure the entire population.

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Section 1.1 "An Overview of Statistics" These are the vocabulary words you need to understand for this section:

SampleStatistic PopulationParameterDescriptive StatisticsInferential Statistics

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1.1 An Overview of Statistics

Objectives

• Define statistics• Distinguish between a population and a sample• Distinguish between a parameter and a statistic• Distinguish between descriptive statistics and inferential statistics

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The entire group of subjects of interest in a research study

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Richmond, VA -- Bob McDonnell holds a steady advantage over Creigh Deeds, 42% to 50%, in the latest Gallup Poll Daily of general election preferences among registered voters.

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Parameter VS Statistic

A PARAMETER is a measurement of the entire populationOften we don't know the actual parameters.

A STATISTIC is a measurement of the sample taken from a population. We use statistics to estimate population parameters.

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Example:

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Vocabulary Words:population- All 100 hyenasparameter-A measurement of a population. How many are females?

Let's say this table of numbers representsthe last 100 spotted hyenas still living. The ones that are highlighted represent the onesthat are female. Animal researchers are concerned that the number of femalesis too low for the species to survive.

So the parameter is _________

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Since it is too difficult to catch all 100 hyenas and count how many are girls,we need to take a sample, and see how many of those are girls. Choose a random sample of size 10.

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sample-The 10 hyenas statistic-The number that describes a sample. What proportion of our samplewere girls?

So our statistic is ____________

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