Sango Stats
Hypothesis Testing [Critical Value Method]
Claim about a single standard deviation.
Basic Steps of Hypothesis Testing
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Identify the claim
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Write out the hypothesis and label the original claim and counter claim
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Left tail, Right tail, or Two tailed test?
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Identify the critical value
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Calculate the test statistic
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Decide – Reject or Fail to Reject the Null Hypothesis
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Conclude – Tie it back to the original claim
Example:
The Wizard’s College of Atlantis is conducting a study to understand the effects of green magic stones in stabilizing fire spells. They measured the flame length of 30 fire spells and found the following:
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The average flame length: 5 feet
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The standard deviation of flame length: 1.5 feet
Using a significance level of 0.05, test the claim that the standard deviation of flame length when using green magic stones is greater than 1.4 feet, which is the minimum safety requirement set by the college.
1. Identify the claim
The standard deviation of green magic stones is greater than 1.4
2. Write out the hypothesis and label the original claim and counter claim
3. Left tail, Right tail, or Two tailed test?
Right Tail
4. Identify the critical value
42.557
5. Calculate the test statistic
6. Decide – Reject or Fail to Reject the Null Hypothesis
We Fail to Reject the Null Hypothesis because the test statistic is not in the rejection zone
7. Conclude – Tie it back to the original claim
There is not enough evidence to support the claim that the standard deviation of green magic stones is greater than 1.4 feet