A conceptual understanding of the T Test. . . some of these ideas are modified from Trochim, W. . . http://www. socialresearchmethod s. net/research/reshome. htm
Check out his web site. . .

Comments

Posting comment...

Premium member

Presentation Transcript

The t-Test for Differences Between Groups :

The t-Test for Differences Between Groups

The t-Test :

The t-Test Tests whether the means of two groups are statistically different from each other

Statistical Analysis :

Statistical Analysis

Statistical Analysis :

Statistical Analysis Control
group
mean

Statistical Analysis :

Statistical Analysis Control
group
mean Treatment
group
mean

Statistical Analysis :

Statistical Analysis Control
group
mean Treatment
group
mean Is there a difference?

What Does Difference Mean? :

What Does Difference Mean?

What Does Difference Mean? :

What Does Difference Mean? Medium
variability

What Does Difference Mean? :

What Does Difference Mean? Medium
variability High
variability

What Does Difference Mean? :

What Does Difference Mean? Medium
variability High
variability Low
variability

What Does Difference Mean? :

What Does Difference Mean? Medium
variability High
variability Low
variability The mean difference
is the same for all
three cases.

What Does Difference Mean? :

What Does Difference Mean? Medium
variability High
variability Low
variability Which one shows
the greatest
difference?

What Does Difference Mean? :

What Does Difference Mean? A statistical difference is a function of the difference between means relative to the variability.
A small difference between means with large variability could be due to chance.
Like a signal-to-noise ratio. Low
variability Which one shows
the greatest
difference?

What Do We Estimate? :

What Do We Estimate? Low
variability

What Do We Estimate? :

What Do We Estimate? Low
variability Signal Noise

What Do We Estimate? :

What Do We Estimate? Low
variability Signal Noise Difference between group means =

What Do We Estimate? :

What Do We Estimate? Low
variability Signal Noise Difference between group means Variability of groups =

What Do We Estimate? :

What Do We Estimate? Low
variability Signal Noise Difference between group means Variability of groups = = M1 – M2 s(M1 – M2)

What Do We Estimate? :

What Do We Estimate? Low
variability Signal Noise Difference between group means Variability of groups = M1 – M2 s(M1 – M2) = = t-value

What Do We Estimate? :

What Do We Estimate? The t-test, one-way Analysis of Variance (ANOVA) and a form of regression all test the same thing and can be considered equivalent alternative analyses.
The regression model is emphasized here because it is the most general. Low
variability

You do not have the permission to view this presentation. In order to view it, please
contact the author of the presentation.

Send to Blogs and Networks

Processing ....

Premium member

Use HTTPs

HTTPS (Hypertext Transfer Protocol Secure) is a protocol used by Web servers to transfer and display Web content securely. Most web browsers block content or generate a “mixed content” warning when users access web pages via HTTPS that contain embedded content loaded via HTTP. To prevent users from facing this, Use HTTPS option.