chapter 11 t (ea) for two: tests between the means of different groups part iv significantly...
TRANSCRIPT
![Page 1: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/1.jpg)
Chapter 11 t(ea) for Two:
Tests Between the Means of Different Groups
Part IVSignificantly Different:
Using Inferential Statistics
![Page 2: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/2.jpg)
What you will learn in Chapter 11
When to use a t testHow to compute the observed t valueInterpreting the t value and what it means
![Page 3: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/3.jpg)
t Test for Independent SamplesDetermining the correct statistic
![Page 4: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/4.jpg)
Computing the Test Statistic
Numerator is the difference between the means
Denominator is the amount of variation within and between each of the two groups
2 2
D
D ( D)1
tn
n
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Degrees of Freedom
The degrees of freedom approximates the sample size
Degrees of freedom can vary based on the test statistic selected
For this procedure…n1 – 1 + n2 – 2
![Page 6: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/6.jpg)
So How Do I Interpret…
t (58) = -.14, p > .05
t represents the test statistic used58 is the number of degrees of freedom-.14 is the obtained value (from the formula)p > .05 indicates the probability
![Page 7: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/7.jpg)
Special Effects…
Effect size is a measure of how different two groups are from one another
Standardized difference between two group means
Jacob Cohen
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Computing Effect Size
Small = 0.0 - .20Medium = .20 - .50Large = .50 and above
1 2ES
X X
SD
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Effect Size Calculator
http://web.uccs.edu/lbecker/Psy590/escalc3.htm
![Page 10: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/10.jpg)
Using the ComputerComputing a t Test using SPSS
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SPSS OutputWhat does it all mean?
![Page 12: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/12.jpg)
Glossary Terms to Know
Degrees of freedomt Test
Independent t TestObtained valueCritical value
Effect size
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Chapter 12 t(ea) for Two (Again):
Tests Between the Means of Related Groups
Part IVSignificantly Different:
Using Inferential Statistics
![Page 14: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/14.jpg)
What you will learn in Chapter 12
When to use a t test for dependent meansHow to compute the observed t valueInterpreting the t value and what it means
![Page 15: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/15.jpg)
t Test for Dependent SamplesDetermining the correct statistic
![Page 16: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/16.jpg)
Computing the Test Statistic
Numerator reflects the sum of the differences between two groups
1 2
2 21 1 1 2 1 2
1 2 1 2
,( 1) ( 1)
2
X Xt
n s n s n n
n n n n
![Page 17: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/17.jpg)
Degrees of Freedom
The degrees of freedom approximates the sample size
Degrees of freedom can vary based on the test statistic selected
For this procedure…n – 1 (where n is the number of observations)
![Page 18: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/18.jpg)
So How Do I Interpret…
t (24) = 2.45, p > .05
t represents the test statistic used24 is the number of degrees of freedom2.45 is the obtained value (from the formula)p > .05 indicates the probability
![Page 19: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/19.jpg)
Using the ComputerSPSS and Paired Samples t Test
![Page 20: Chapter 11 t (ea) for Two: Tests Between the Means of Different Groups Part IV Significantly Different: Using Inferential Statistics](https://reader036.vdocuments.us/reader036/viewer/2022081515/56649e4e5503460f94b44bde/html5/thumbnails/20.jpg)
SPSS OutputWhat does it all mean?