Unit 5 Practice: Correlation 1

Unit 5: Correlation

• Practitioners Work in Online Calculator, Excel, or SPSS

Photo source: http://media.photobucket.com/image/leader/kbardes/CELEBRATE-THE-LEADER-COLOR.jpg

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Error: All research has errors.• LESS SERIOUS: A type I error occurs when

the null hypothesis is rejected when it is in fact true; that is, Ho is wrongly rejected.

• MORE SERIOUS: Type II error occurs when the null hypothesis H0, is not rejected when it is in fact false.

• A type II error is frequently due to sample sizes being too small.

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Begin by taking this measure just so you know the test we’re using for the scenario. The test also may be interesting and give you insight into your own leadership behavior.

• Take this test on leadership: http://www.testcafe.com/lead/lead.html

• Question to answer in discussion:

What level of data does this test provide?

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Q. What level of data does this test provide?

A. Nominal because it’s categories.

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There would actually be 15 categories in this case, which makes for a complicated example.

1. Diligence - How hard do you work? 2. Persistence - For how long will you work to achieve your goal? 3. Understanding - Can you listen to others’ problems? 4. Confrontation - Do you have problems confronting adversaries? 5. Public Speaking - Can you stand in front of crowds and talk to them? 6. Problem Solving - Are you able to find appropriate solutions? 7. Role Model - Do people look up to you and your values? 8. Disposition - Are you easy to get along with? 9. Flexibility - Can you change your schedule according to group majority? 10. Ambition - Do you ever settle for mediocrity? 11. Organization - Can you keep a schedule for you and your followers? 12. Punctuality - Are you on time for your appointments? 13. Loyalty - Do you drop out of programs or change votes? 14. Street Smarts - Can you hold your own voice in the real world? 15. Versatility - Are you a jack of all trades or a master of none?

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Remember, these are the choices for types of data.• http://www.stat.sfu.ca/~cschwarz/Stat-

301/Handouts/node5.html• 1 Nominal measurement (names)• 2 Ordinal measurement (order)• 3 Interval measurement (constant

scale)• 4 Ratio measurement (natural zero)

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Least sophisticated (low level)• 1 Nominal measurement is just

categories or “names” • 2 Ordinal measurement is rank order • 3 Interval measurement is rank with

equal intervals• 4 Ratio measurement has an absolute

zero (not typically used in communication studies)

Most sophisticated (high level)

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Correlation• A correlation shows the strength of the

relationship between two variables (-1 to +1). • .8 is an extremely strong positive relationship

(same direction)• -.8 is an extremely strong negative

relationship (opposite direction)

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• In the upper left diagram, there is a strong correlation or relationship (notice how close the data are in the line)

• In the lower right diagram below, there is a weak relationship (notice how the data are all over the place). For more information, see http://www.statsoft.com/textbook/stb

asic.html

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Let’s say that everyone in the class came up with one of two categories as their strongest.

1. Persistence or 2. LoyaltyOddly, everyone in the class had either high

communication apprehension (CA) or low communication apprehension on a separate measure of CA.

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Let’s imagine 20 students took the test and the data looked like this for the class.

Loyalty Persistence

High Communication Apprehension

18 2

Low Communication Apprehension

1 19

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Another way to see the data.

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Online Calculatorhttp://www.stattucino.com/calculate/correlations.html

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Results

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There’s a relationship.

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Or use SPSS “Statistics Coach” (Under “Help”). We want to identify significant relationshps between variables.

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Nominal data (catgories)

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There’s a correlation

• Available by Sunday.

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Or Use Excel

• Open Excel (Microsoft Office)• Depending on your version, go to

“Tools”• Select “Data Analysis” If you don’t

have it, select “Add-ins” and select “ToolPack” to add. Go back to Tools and select Data Analysis now.

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Select “Correlation.”

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Interpretation of Results in Hypothetical Study

• People with high communication apprehension are more likely to be strongest in the loyalty leadership attribute.

• People with low communication apprehension are more likely to be strongest in the persistence attribute.

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What statistical test should we run?

• Remember, the first thing you need to do is determine the type of statistical test needed.

• You make this decision based on the type of measurement, variables, and what you want to accomplish.

• You can use help like this http://www.microsiris.com/Statistical%20Decision%20Tree/

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