Validity and Reliability

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# Validity and Reliability
## EDP 612 Week 6
### Dr. Abhik Roy

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#  <span style="color:#d9534f;font-weight:bold;">Reliability</span> and <span style="color:#428bca;font-weight:bold;">Validity</span>

+ <span style="color:#d9534f;font-weight:bold;">Reliability</span> and <span style="color:#428bca;font-weight:bold;">Validity</span> are important concepts in both measurement and the full experiment to insure the link between our statistics and conclusions is sound.

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<span style="color:#d9534f;font-weight:bold;">Reliability</span><br><br><i>being consistent</i>
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<span style="color:#428bca;font-weight:bold;">Validity</span><br><br><i>on target</i>
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# <span style="color:#d9534f;font-weight:bold;">Reliability</span>

+ <span style="color:#d9534f;font-weight:bold;">Reliability</span> is the extent to which the measurements of a test remain consistent over repeated tests of the same subject under identical conditions.

+ *Officially*. An experiment is reliable if it yields consistent results of the same measure. It is unreliable if repeated measurements give different results.

+ *Lay terms* Results aren’t just a one-off
	
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+ *Day to day example*. A car
	
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+ *Research world example*. Reliability of experiment, replication, and error rate

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#  <span style="color:#428bca;font-weight:bold;">Validity</span>

+ <span style="color:#428bca;font-weight:bold;">Validity</span> of a measure is the degree to which the variable measures what it is intended to measure

+ *Officially*. An experiment is valid if it yields outcomes suitable for answering original questions
	
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+ *Lay terms*. Do the results answer what is supposed to be answered?

+ *Day to day example*. Medical results

+ *Research world example*. Validity of standardized test scores, research results and findings

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No <span style="color:#d9534f;font-weight:bold;">Reliability</span> and Not <span style="color:#428bca;font-weight:bold;">Valid</span>
![](img/image10.png)

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<span style="color:#d9534f;font-weight:bold;">Reliable</span> but No <span style="color:#428bca;font-weight:bold;">Validity</span>
![](img/image12.png)

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Low <span style="color:#d9534f;font-weight:bold;">Reliability</span> and Possibly High <span style="color:#428bca;font-weight:bold;">Validity</span>
![](img/image13.png)

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<span style="color:#d9534f;font-weight:bold;">Reliable</span> and <span style="color:#428bca;font-weight:bold;">Valid</span>
![](img/image14.png)

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#  Two important points

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A test can be <span style="color:#d9534f;font-weight:bold;">Reliable</span> without being <span style="color:#428bca;font-weight:bold;">Valid</span>.
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+ A test cannot be <span style="color:#428bca;font-weight:bold;">Valid</span> unless it is <span style="color:#d9534f;font-weight:bold;">Reliable</span>.
]

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#  That’s it!

Any questions?