Confidence (8.1)
You have a confidence level of 95%, what does this mean about the confidence interval?
95% of the data, centered around the average, fits within the confidence interval
What do you have to do to the sample size when working with a t-distribution
Subtract it by one/find Degrees of Freedom
If you have a 98% confidence interval, what is the area of the left tail
1% or 0.01
How does Chi Squared distribution differ from Normal Distribution
It is asymmetrical
How do you interpret a P-Value of .800?
You fail to reject the null, accept the null, or your treatment had no effect.
This letter of the alphabet is used when you are measuring how far away a number is from a non-probability dataset. "It is almost always some version of 2"
Z
This letter of the alphabet is used when measuring how far away a number is from a probability based dataset. "It is almost always some version of 2"
T
How do you calculate p-hat?
x/n
Which of these values can be negative?
Z-Score
T-Score
Chi Squared Score
Z-Score and T-Score can be negative
How do you interpret a p-value of 0.002?
You reject the null hypothesis
What can you infer from a data point where the z-score is equal to zero?
The average is equal to the data point
How does the graph of a z-distribution compare to the graph of a t-distribution at small sample sizes
DOUBLE POINTS: Explain why this change occurs
A t-distribution is more spread out at small sample sizes
This is because the sample standard deviation is random in a t-distribution, causing a wider distribution in the sample
Find the sample size needed for a 95% confidence interval (Z-score of 1.96) to have a margin of error of 0.025
n = 0.25(Z-Score / margin of error) ^2
A sample size of 1537 is needed
Can Chi Squared be skewed to the Left?
No
What is a Type I error?
The calculator steps for finding the confidence interval of a Z-Score
STAT > TESTS > 7:ZInterval > Input Data > Calculate
The calculator steps for finding confidence interval of a t-score
STAT > TESTS > 8:TInterval > Input Data > Calc
The calculator steps for finding a probability proportion
STAT > TESTS > A:1-PropZInt > Input Data > Calc
The calculator steps for finding the confidence interval of a chi squared test
MATH > C: Numeric Solver > Put in 0 for E1 > Enter > 2nd > Vars > 8:X2cdf Input 0 for lower bound and X for upper bound, input DF > Enter > add minus alpha/2 > Enter > Alpha > Enter
What is a Type II Error?
Accepting the null when it is really false (False Negative)
The mean of a dataset is 149 and the standard deviation is 21 with a sample size of 9. Find the confidence intervals with a confidence of 90%.
(137.49, 160.51)
The sample mean of a dataset is 149 and the sample standard deviation is 21 with a sample size of 9. Find the confidence intervals with a confidence of 90%
(135.98, 162.02)
574 of 600 students surveyed believe that STATS is useful for their degree. Construct a 95% confidence interval for the proportion of students that think STATS is useful for their degree.
(0.9404, 0.9726)
(1121.1, 13095.5)
For my senior project, I did some treatments and ran a statistical test, which gave me a p-value of 0.15, did my treatments have a notable effect on the data?