One sample t-test
What is this df=n-1
Degrees of freedom
What is the advantage of using repeated samples tests?
More statistical power for detecting effects
What makes the independent t-test differ from the rest of the t-tests?
we do not have any known population, we have two samples that are independent and we want to know if the samples are from the same or different populations
What does the null hypothesis state?
Nothing happens, treatment has no effect
What is a type I error?
rejecting the null hypothesis
What is the purpose of rpb2?
Finding the effect size (how important the relationship is)
What is it called when the researcher matched the participants that are put into the two groups?
Matched samples
If you want to check whether the homogeneity of variance assumption has been met when running an independent t-test, we should calculate?
Hartley's F-Max test for variance equality
What does “tcrit“ define?
The region of rejection
What error is it called when you are failing to reject the null Hypothesis?
Type II error
When do we use a t-test over a z-test?
When standard deviation is unknown but standard error is known
Why would we preform a related t-test even though it’s very similar to the single sample t-test?
when we have 2 samples that are related and we want to know whether the samples came from the same or different populations so we calculate the difference scores.
In the independent t-test, what is the point estimate?
A single best estimate for the difference between the means of the two unknown populations
When a statistic falls in the region of rejection we…
What error is a false alarm?
Type I
What are confidence intervals used for?
To give us a range in which the population mean probably falls
What two problems that can be addressed with using counterbalancing the order of the presentation of the treatments?
Carry-over effects
Progressive error
What do we call the range within which the difference between the means of the two unknown populations probably falls?
Interval estimate
What role does variability in raw scores play in hypothesis testing?
impacts the ability to correctly reject the null hypothesis
What type of error happens when a researcher might give up on a hypothesis that is truly correct?T
Type II
X̄ = 66.57, sx = 8.43, mx = 71.43, n = 15
Calculate the estimated standard error:
Calculate the tobt:
2.18
-2.23
D̄ = 13, sD = 15.33, nD = 8
Calculate the standard error of the difference scores:
Calculate tobt:
5.42
2.40
SSm= 8264.96, dfm= 21, SSf= 9773.63, dff= 23
Calculate the pooled standard deviation:
Calculate standard error of the difference between means:
Calculate tobt:
20.25
5.98
-2.48
TxWes staff are sick of seeing students being miserable on campus around final exams so they decide to get some emotional support dogs to hang out with students during Finals Week to lower their stress.
After their visit with the dogs, 15 students’ Perceived Stress Scale score was measured (X̄ = 12.6, sX = 4.3). Prior research says the average (mX) Perceived Stress Scale score for exam preparation situations is 17. Using a = .01, did the pups reduce the students’ stress?
State the Hypotheses
H0: μpups ≥ mall (17)
Ha: μpups < μall (17)
1 - β (one minus Type II error rate) is also called the…
Power of a test