Stats Test 2 Flashcards
What does the symbol m stand for?
margin of error
As sample size increases, what happenes to m?
decreases
As confidence increases, what happenes to m?
increases
What does a hypothesis test or significance test do?
Tells us if there’s a real difference (not a significant difference.)
if p <= a…
Reject Ho
if p > a…
Fail to reject Ho due to insufficient evidence
What is the related measure of certainty?
alpha or a
What are the degrees of freedom?
sample size - 1 or n - 1
What is the result of a confidence interval test
a confidence interval using a margin of error
What is the result of a Hypothesis test
Reject or fail to reject
For statistical inference, what conditions must be met?
Randomness and Normal population or Large sample (n>=30)
Examples of natural variation
Raw material, human performance, equipment performance measurement
Examples of unnatural variation
Bad batch, broken machine, poorly trained operator
What are generally the bounds for a control chart?
+3sd and -3sd
Under what conditions does a control chart fail
One point outside of the limits or nine points on one side in a row
Estimator
A general statistic that estimates the parameter (x bar or s)
Estimate
A specific value of an estimator
Confidence interval wording
We are % confident that x lies between a and b
What does NOT go into confidence interval wording
Probability (in terms of the confidence percentage) (It’s either right or it’s wrong)
What is standard error
s/sqrt(n)
What is margin of error
t * s/sqrt(n)
What is the significance of alpha?
It is the chance of rejecting a correct null hypothesis
What is the effect size?
x(bar) - mu
Two sided test require…
More evidence than a one sided test
Confidence tests and Hypothesis tests only agree if
If Ha is two sided and
Confidence % + a = 1
What type of error is a Type I error?
H0 is true but gets rejected
What type of error is a Type II error?
H0 is not true but fails to be rejected
What is the representation of the chance of a Type I error?
alpha
What is the representation of the chance of a Type II error?
beta
What is power?
the inverse of beta (1 - beta), or the chance to reject a null hypothesis if it is false
What is the relationship between alpha and beta?
Inverse
What is the relationship between alpha and Power?
Direct
