Section 7.7 Introduction to Inference - PowerPoint PPT Presentation

Title:

Section 7.7 Introduction to Inference

Description:

Statistical Inference. Statistical inferencerefers to methods for drawing conclusions about an entire population on the basis of data from a sample. – PowerPoint PPT presentation

Number of Views:152
Avg rating:3.0/5.0
Slides: 16
Provided by: pbwo778
Category:
Tags:
Transcript and Presenter's Notes

Title: Section 7.7 Introduction to Inference

1
Section 7.7Introduction to Inference
• Special Topics

2
Statistical Inference
• Statistical inference refers to methods for
drawing conclusions about an entire population on
the basis of data from a sample.
• Since populations are usually too large for us to
get 100 accurate information (that is, to survey
everyone!), we use results from sampling to get
an estimate of what true population values are.
• Statistical inference works only if the data come
from a random sample or randomized comparative
experiment.

3
Confidence Intervals
• A confidence interval is one type of inference
method.
• A confidence interval is a range of values,
calculated from sample data, where we believe a
true population value might actually be, with a
certain level of confidence.
• True population values are called parameters.

4
Parameters vs. Statistics
• A parameter is a fixed (usually unknown) number
that describes a population.
• A statistic is a number that describes a sample.
The value of a statistic is known when we have
taken a sample, but it can change from sample to
sample. We often use a statistic to estimate an
unknown parameter.
• Example 15 - Do You Find Shopping Frustrating?

5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
Example 16
9
(No Transcript)
10
(No Transcript)
11
Sampling Distribution
• The sampling distribution of a statistic is the
distribution of values taken on by the statistic
in all possible samples of the same size from the
same population.
• We want to describe sampling distributions for