Confidence Intervals
If I change the z-value corresponding to my confidence interval, it has this affect on my confidence interval:
It changes the level of confidence we have that the true value lies in my confidence interval.
The 3 most common alpha-levels are:
0.1, 0.05, and 0.01
This test is used instead of a z-test when the sampling size is too small for the central limit theorem to ensure normality.
A t-test
The Standard Deviation of a Proportional Sampling Distribution Is:
((p(1-p))/n)^(1/2)
If I decrease the alpha-level, this type error becomes more likely:
Type 2
A range of values that is expected to contain the true population parameter with a specified level of confidence.
A Confidence Interval
A z-test and a t-test are useful when using _____ variables, and a proportional-test is useful when using _____ variables.
Quantitative, Categorical
The Statistical Criteria for Analysis of a t-test is:
1 - The underlying phenomena must be normally distributed
2 - 2<n<30
3 - n<N/10
The "pooled-proportion" formula is:
(x1+x2)/(n1+n2)
A Type 1 error is the following:
A false positive
1.645, 1.960, 2.575
Just because the results of a statistical test are found to be statistically significant doesn't mean that they are ______.
Practically Significant.
The Statistical Criteria for Analysis of a z-test is:
1 - n>30
2 - n<N/10
The Statistical Criteria for Analysis of a proportional-test is:
1 - n>30
2 - n<N/10
3 - np>10
4 - n(1-p)>10
The Null-Hypothesis represents the idea that the differences we see in the data is a product of this.
Sampling Variability
A 90% confidence interval.
If statistical criteria for analysis is not met, or statistical significance is not found, we may still claim that a studies results are ______.
Indicative
This statistical concept explains why a t-test approaches a z-test as the sample size increases, and is also related to why normal distributions appear in nature.
The Central Limit Theorem
If a proportional sampling distribution "crosses" over the line p = 0 significantly, than this statistical criteria for analysis was probably violated:
np>10
If I increase the alpha-level, this type error becomes more likely:
Type 1
Ford Motor Company claims that their cars have less defects than Honda. Researchers test this claim, testing engines for defects off the assembly line. 200 Ford SUV's are tested, and 18 are found to have defects. 600 Honda SUV's are tested, and 27 are found to have defects. Find a confidence interval for the difference in defects.
[0.00201, 0.08799]
We reject the Null Hypothesis if ____ is less than ____.
p-value, alpha-level
A pizza company claims that its pizza is always "Hot-N-Read", with an average temperature of at least 175 degrees at point of sale. Mr. Tyler doubts this claim, believing that they sell their pizzas colder than this. He buys 100 pizzas, and finds they have an average temperate at point of sale of 168 degrees, with a sample standard deviation of 15. This is the p-value.
Approximately 0.
A High School claims that 70% of their students pass their grade each year. A simple random sample of 105 students at the school found that 77 of them passed their grade. Find the p-value.
0.77197
This error occurs when you fail to reject the null-hypothesis, even though it is actually false.
Type 2 error