Izabela Szlachta at 17:03, 3 February 2012

2012-02-03T17:03:48Z

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{{Cat|Hypothesis Testing| 091}}

Prerequisites
* [[Introduction to Hypothesis Testing]], [[Statistical Significance]], [[Type I and II Errors]]

'''Questions'''
* Why the probability value is not the probability the null hypothesis is false?
* Why a low probability value does not necessarily mean there is a large effect?
* Why a non-significant outcome does not mean the null hypothesis is probably true?

{{Collapse|Misconception 1: The probability value is the probability that the null hypothesis is false|
* The probability value is the probability of a result as extreme or more extreme given that the null hypothesis is true
* It is the probability of the data given the null hypothesis
* It is NOT the probability that the null hypothesis is false.
}}

{{Collapse|Misconception 2: A low probability value indicates a large effect|
* A low probability value indicates that the sample outcome (or one more extreme) would be very unlikely if the null hypothesis were true. A low probability value can occur with small effect sizes, particularly if the sample size is large.
}}

{{Collapse|Misconception 3: A non-significant outcome means that the null hypothesis is probably true|
* A non-significant outcome means that the data do not conclusively demonstrate that the null hypothesis is false
}}

== Questions ==

<quiz display=simple >
{A low probability value indicates a large effect.
|type="()"}
- True
+ False

{
{{Show Answer|
A low probability value indicates that the sample outcome (or one more extreme) would be very unlikely if the null hypothesis were true. A low probability value can even occur with small effect sizes, particularly if the sample size is large.
}}
}

{The probability value represents the probability of the null hypothesis given the data.
|type="()"}
- True
+ False

{
{{Show Answer|
The probability value represents the probability of the data given the null hypothesis.
}}
}

{A non-significant outcome means that the data do not conclusively demonstrate that the null hypothesis is false.
|type="()"}
+ True
- False

{
{{Show Answer|
This is true, but a common misconception is that a non-significant outcome means that the null hypothesis is probably true.
}}
}

{The probability value is the probability that the null hypothesis is false.
|type="()"}
- True
+ False

{
{{Show Answer|
The probability value is the probability of a result as extreme or more extreme given that the null hypothesis is true. It is the probability of the data given the null hypothesis. It is not the probability that the null hypothesis is false.
}}
}

</quiz>
{{Statistics Links}}

Misconceptions - Revision history

Izabela Szlachta at 17:03, 3 February 2012