Confidence interval and Hypothesis testing for population mean (µ) when is known and n (large)

Содержание

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Lecture overview: Learning outcomes At the end of this lecture you

Lecture overview: Learning outcomes

At the end of this lecture you should

be able to:
7.6.1 Calculate and interpret confidence intervals for a population parameter
7.6.2 Test the hypothesis for a mean of a normal distribution,
Ho: µ=k,
H1: µ≠k or µ>k or µ

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Lecture overview: Learning outcomes At the end of this lecture you

Lecture overview: Learning outcomes

At the end of this lecture you should

be able to:
7.6.3 Test the hypothesis for the difference between means of two independent normal distributions
Ho: µx - µy=0,
H1: µx - µy≠0 or µx - µy<0 or µx - µy>0

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Textbook Reference The content of this lecture is from the following

Textbook Reference

The content of this lecture is from the following textbook:
Chapter

3
Statistics 3 Edexcel AS and A Level Modular Mathematics S3 published by Pearson Education Limited
ISBN 978 0 435519 14 8
Further examples can be found in the textbook.

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Terminology A range of values constructed so that there is a

Terminology

A range of values constructed so that there is a

specified probability of including the true value of a parameter within it

CONFIDENCE INTERVAL

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Terminology Probability of including the true value of a parameter within

Terminology

Probability of including the true value of a parameter within a

confidence interval
Percentage

CONFIDENCE LEVEL

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Terminology Two extreme measurements within which an observation lies End points

Terminology

Two extreme measurements within which an observation lies
End points of the

confidence interval
Larger confidence – Wider interval

CONFIDENCE LIMITS – CRITICAL VALUES

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Estimation of population parameters Point estimate Interval estimate Foundation Year Program

Estimation of population parameters
Point estimate Interval estimate

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We have covered

this
in previous lecture
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Point estimate VS Interval estimate Point estimate Foundation Year Program 2016-17

Point estimate VS Interval estimate

Point estimate

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But, sample mean is

still an approximation, and how close (ERROR) it is to true population mean value we do not consider in the Point estimate.
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Point estimate VS Interval estimate Point estimate Foundation Year Program 2016-17 Interval estimate

Point estimate VS Interval estimate

Point estimate

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Interval estimate

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Point estimate VS Interval estimate Foundation Year Program 2016-17 Interval estimate

Point estimate VS Interval estimate

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Interval estimate

In interval estimate we

do consider ERROR

Interval estimate is a range of numbers around the point estimate within which the parameter is believed to fall

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Point estimate VS Interval estimate Point estimate Foundation Year Program 2016-17

Point estimate VS Interval estimate

Point estimate

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Interval estimate

Until now we

didn’t specify what is meant by error
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Point estimate VS Interval estimate Point estimate Foundation Year Program 2016-17 Interval estimate Standard error

Point estimate VS Interval estimate

Point estimate

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Interval estimate

Standard error

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7.5.1 Calculate and interpret confidence intervals for a population parameter Interval

7.5.1 Calculate and interpret confidence intervals for a population parameter

Interval estimate

provides us interval within which we believe value of true population mean falls
Then by using Standard Normal Distribution we can consider specific level of confidence that µ is really there by adjusting critical coefficient

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The general formula for all confidence intervals are: Point Estimate ±

The general formula for all confidence intervals are:

Point Estimate ± (Critical

Value) (Standard Error)

7.5.1 Calculate and interpret confidence intervals for a population parameter

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7.5.1 Calculate and interpret confidence intervals for a population parameter Foundation Year Program 2016-17 Critical values

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Critical values

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Empirical rule Foundation Year Program 2016-17

Empirical rule

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Empirical rule Foundation Year Program 2016-17

Empirical rule

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95% Confidence Interval of the Mean Bluman, Chapter 7 Foundation Year Program 2016-17 ? ?

95% Confidence Interval of the Mean

Bluman, Chapter 7

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?

?

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Common Levels of Confidence Bluman, Chapter 7 Foundation Year Program 2016-17

Common Levels of Confidence

Bluman, Chapter 7

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Formula for the Confidence Interval of the Mean for a Specific

Formula for the Confidence Interval of the Mean for a Specific

α

Bluman, Chapter 7

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For a 90% confidence interval:

For a 99% confidence interval:

For a 95% confidence interval:

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7.5.1 Calculate and interpret confidence intervals for a population parameter Foundation Year Program 2016-17 Example 1

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Example 1

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7.5.1 Calculate and interpret confidence intervals for a population parameter Foundation Year Program 2016-17 Example 1

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Example 1

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7.5.1 Calculate and interpret confidence intervals for a population parameter Foundation Year Program 2016-17 Example 2

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Example 2

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7.5.1 Calculate and interpret confidence intervals for a population parameter Foundation Year Program 2016-17 Example 2

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Example 2

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Hypothesis testing as well as estimation is a method used to

Hypothesis testing as well as estimation is a method used to

reach a conclusion on population parameter by using sample statistics.

7.5.2 Test the hypothesis for a mean of a normal distribution

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Hypothesis testing

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In Hypothesis testing beside sample statistics level of significance (α) is

In Hypothesis testing beside sample statistics level of significance (α) is

used to make a meaningful conclusion.

7.5.2 Test the hypothesis for a mean of a normal distribution

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Hypothesis testing

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The level of significance, α, is a probability and is, in

The level of significance, α, is a probability and is, in

reality, the probability of rejecting a true null hypothesis. 
Confidence level
C = (1- α)
Level of Significance 
α =  1 - C

Level of Significance (α)

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In Hypothesis testing we compare a sample statistic to a population

In Hypothesis testing we compare a sample statistic to a population

parameter to see if there is a significant difference.

7.5.2 Test the hypothesis for a mean of a normal distribution

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Hypothesis testing

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1. Hypothesis testing can be used to determine whether a statement

1. Hypothesis testing can be used to determine
whether a statement

about the value of a
population parameter should or should
not be rejected.

2. The null hypothesis, denoted by H0 , is a tentative
assumption about a population parameter.

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7.5.1 Calculate and interpret confidence intervals for a population parameter

Hypothesis testing

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3. The alternative hypothesis, denoted by Ha, is the opposite of

3. The alternative hypothesis, denoted by Ha, is the
opposite

of what is stated in the null hypothesis.

4. The hypothesis testing procedure uses data
from a sample to test the two competing
statements indicated by H0 and Ha.

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Hypothesis testing

7.5.1 Calculate and interpret confidence intervals for a population parameter

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Types of Hypothesis testing Null Hypothesis (H0) Alternative Hypothesis (Ha or

Types of Hypothesis testing

Null Hypothesis (H0)
Alternative Hypothesis (Ha or

H1)
Each of the following statements is an example of a null hypothesis and corresponding alternative hypothesis.

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Step 1. Develop the null and alternative hypotheses. Step 2. Specify

Step 1. Develop the null and alternative hypotheses.

Step 2. Specify the

level of significance α.

Step 3. Collect the sample data and compute the value of the test statistic.

p-Value Approach

Step 4. Use the value of the test statistic to compute the
p-value.

Step 5. Reject H0 if p-value < a.

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Steps of Hypothesis Testing

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Foundation Year Program 2016-17 Steps of Hypothesis Testing Critical Value Approach

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Steps of Hypothesis Testing

Critical Value Approach

Step 4. Use the

level of significance to determine the critical value and the rejection rule.

Step 5. Use the value of the test statistic and the rejection
rule to determine whether to reject H0.

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p-Value Approach to One-Tailed Hypothesis Testing Reject H0 if the p-value

p-Value Approach to
One-Tailed Hypothesis Testing

Reject H0 if the p-value <

α .

The p-value is the probability, computed using the
test statistic, that measures the support (or lack of
support) provided by the sample for the null
hypothesis.

If the p-value is less than or equal to the level of
significance α, the value of the test statistic is in the
rejection region.

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Critical Value Approach to One-Tailed Hypothesis Testing The test statistic z

Critical Value Approach to
One-Tailed Hypothesis Testing

The test statistic z

has a standard normal probability
distribution.

We can use the standard normal probability
distribution table to find the z-value with an area
of α in the lower (or upper) tail of the distribution.

The value of the test statistic that established the
boundary of the rejection region is called the
critical value for the test.

The rejection rule is:
Lower tail: Reject H0 if z < -zα
Upper tail: Reject H0 if z > zα

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One-tailed test (left-tailed) Foundation Year Program 2016-17

One-tailed test (left-tailed)

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One-tailed test (right-tailed) Foundation Year Program 2016-17

One-tailed test (right-tailed)

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Two-tailed test Foundation Year Program 2016-17

Two-tailed test

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7.5.2 Test the hypothesis for a mean of a normal distribution,

7.5.2 Test the hypothesis for a mean of a normal distribution,

Ho: µ=k, H1: µ≠k or µ>k or µ

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Example 3

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Example 3

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Example 3

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Example 4

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Example 4

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Example 4

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Example 4

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Example 4

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7.5.2 Test the hypothesis for a mean of a normal distribution,

7.5.2 Test the hypothesis for a mean of a normal distribution,

Ho: µ=k, H1: µ≠k or µ>k or µ

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Example 5

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Example 5

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Example 5

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Example 5

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7.5.3 Test the hypothesis for the difference between means of two

7.5.3 Test the hypothesis for the difference between means of two

independent normal distributions

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7.5.3 Test the hypothesis for the difference between means of two

7.5.3 Test the hypothesis for the difference between means of two

independent normal distributions

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7.5.3 Test the hypothesis for the difference between means of two

7.5.3 Test the hypothesis for the difference between means of two

independent normal distributions

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Example 6

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Example 6