Column 1
A p-value is the probability of observing a value of a statistic or a value that is more unusual just by chance, assuming the null hypothesis is true?
True
The larger the p-value the more significant the result.
False, smaller
What do you do if the test statistic is less than the negative critical value or greater than the positive critical value?
Reject the null hypothesis
What do you do if the p-value is less than the level of significance?
Reject the null hypothesis
What will cause the critical value to change?
If you change the level of confidence
What is a Type 1 Error?
Rejecting a true null hypothesis
What is a Type 2 Error?
Accepting a false null hypothesis
How do you know when to do a T-test and when to do a Z-test?
You use a T-test when Sigma or the population standard deviation is not known, you do the Z-test when the population standard deviation is known.
How do you know when to use a two tailed, right-tailed, or left-tailed test?
You use a two-tailed test when the question states it is looking for something “different” You use a right-tailed test when it is looking for something that is “more than” or “greater than.” You use a left-tailed test when you here “lower than” or “less than”
What excel formula do you use to find a critical value for a two-tailed test when Sigma is known?
=ABS(NORM.S.INV(α/2)
What is the risk called where a researcher fails to reject an invalid null hypothesis?
The beta risk
What is the Power of the Test?
The probability of correctly rejecting an invalid null hypothesis
What excel formula do you use to find a p-value for a left-tailed test when Sigma is unknown?
=T.DIST(t test statistic,n-1,TRUE)
What excel formula do you use to find a p-value for a right-tailed test when dealing with a proportion?
=1-NORM.S.DIST(z test statistic, TRUE)
What excel formula do you use to find a critical value for a right-tailed test when Sigma is known?
=ABS(NORM.S.INV(α)
What excel formula do you use to find a p-value for a two-tailed test when Sigma is unknown?
=T.DIST.2T(ABS(t test statistic),n-1)
Assuming a normal distribution, as the standard deviation increases, the shape of the curve becomes taller and narrower?
False, it actually becomes shorter and wider
As the standard deviation of a normal curve increases, the data becomes more centered around the mean
True
When do we use the standard deviation of the data from the sample?
When sampling and the standard deviation is not known
When does the x-value must be equal to the mean of the distribution?
If the z-score is equal to zero
Why are the mean and median always equal in a normal distribution?
Because it is symmetric
What is the Empirical Rule?
It states that 99.7% of data observed following a normal distribution lie within 3 standard deviations of the mean
Is finding the 90% percentile the same as finding the top 90% of the population?
No, it is actually finding the top 10% of the population
A confidence interval should have a sample size of at least 20
False, the answer is at least 30
Does T Distribution have smaller or larger variance than Normal Distribution
It has a larger variance, and also is flatter/wider