Hypothesis Testing - The Basic Idea

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Category: Education
     
 

Presentation Description

Presents the basic concept of hypothesis testing.

Comments

By: Jennylou (5 month(s) ago)

thanks for the presentation. may u e-mail it to pangilinan.jennylou@yahoo.com

By: Irfan_sibaca (6 month(s) ago)

Excellent !! very easy to understand the concept with your ppt. I Shall be obliged if you could e mail this presentation to irfan_sibaca@rediffmail.com

By: sabhyata (19 month(s) ago)

Excellent way of putting across the concept. Shall be obliged if you could e mail this presentation to drsabhyata@yahoomail.com thanks, Dr Sabhyata

By: uniworld (19 month(s) ago)

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By: shaulakh (21 month(s) ago)

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Presentation Transcript

Slide 1: 

Page 1 Hypothesis Tests Hypothesis Testing 1 - Basic Ideas

Slide 2: 

Page 2 Your friend proposes a series of bets using a coin. Basic Hypothesis Testing She flips… You figure the probability of a head or a tail is 0.50 so there isn’t much of a risk. Heads. You lose. She flips again… 2 Heads. Lucky!. And again… 3 Heads. Very lucky. And again… 4 Heads? Getting suspicious here. And again… 5 Heads!!! OK. That’s it. Something’s wrong here. Turn the coin over… Look at it this way. Hey! Heads on both sides. For only $5, your friend has taught you basic Hypothesis Testing. She chooses HEADs. You agree to bet $1 on each flip.

Slide 3: 

Page 3 Basic Hypothesis Testing You went into this arrangement believing that the coin was fair. In 5 tosses, you would expect a fair coin to come up heads 2 or 3 times, P( 5H out of 5 ) = (0.5)5 = 0.031 0 1 2 3 4 5 No. of Heads but the probability of 5 heads in 5 tosses is only If a fair coin were tossed 5 times, the outcome probabilities would be as shown below. This is so improbable that you would sooner reject your original hypothesis that the coin was fair than believe that such a rare outcome could occur. THAT WAS A BASIC HYPOTHESIS TEST. ok maybe 1 or 4 times,

Slide 4: 

Page 4 Basic Hypothesis Testing We need to consider one important idea. In life, whenever we make a decision, there is ALWAYS a probability that we are WRONG. because even though the probability was small, p=0.031, it was possible for a fair coin to have produced 5 heads in a row. In this hypothesis test, when we rejected the fair coin (Null) hypothesis, we knew that there was a 0.031 probability that we were making the wrong decision . . . Wrongly rejecting the null hypothesis is called a Here, it was p=0.031. Type I error and the probability of making that error is called the p-value.