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Correlation and Regression
Hypothesis Testing
Different Types of Tests to Compare Two samples
Confidence Intervals
Chi-Square Test of Independence
100
The value of Pearson's Correlation Coefficient r tells us the ________ of the relationship between two variables, the +/- symbol next to r tells us the ____________ of the relationship between the two variables.
Strength & Direction (By strength we mean how well the data hug the line of best fit.)
100
What type of test do you use when testing a claim about a population mean who's standard deviation is known?
What is z-test.
100
When testing for inferences about two means we use the _-distribution. There is a different method with the _-distribution depending on whether the two samples are dependent or ___________.
What is the t-distribution. What is independent.
100
What is a confidence interval?
What is an estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data.
100
How do you know if the regression line will be a good model for prediction?
The regression line will be a good model for prediction if the correlation coefficient r is significant.
200
Give an example of a positive correlation and an example of a negative correlation.
Positive- As SAT scores go up, grades on finals go up too. Negative- As two friends argue less their rating of friend satisfaction goes up.
200
What test do you use when testing a claim about a population mean who's standard deviation is unknown?
What is t-test.
200
The two-sample f-test is used to compare __________ in two samples.
What is variance.
200
Interpret the following CI. 95% CI for Mean= (3002.3, 3203.7)
What is "We are 95% confident that the true mean falls between 3002.3 and 3203.7.
200
How do you calculate the df for a chi square test of independence?
What is df= (r-1)(c-1)
300
Correlation does not equal _____________.
What is causation.
300
Define the Null and Alternative Hypothesis for a scientist who wants to see if the new bats she has found have a different mean weight than the other population of bats living in the area.
What is Ho: M1 = M2, Ha: M1 does not equal M2
300
This type of test is used to test claims about a population proportion.
What is z-test.
300
True or False? A Chi Square Goodness of Fit Test can only be used with parametric or continuous data (such as height in inches).
What is False! Chi Square tests can only be used with categorical, non-parametric data. For example you could not divide the data by scores on a test, but you could divide the data up as pass or fail for the test. Additionally, the data in a Chi-square grid should not be in the form of percentages, or anything other than frequency (count) data.
400
What is the formula for the regression line and what does each variable represent?
What is Y'= a + bX where Y' is the predicted value of Y, a is the intercept (the point at which the regression line crosses the Y-axis) and b is the slope of the regression line. X is the hypothetical X value you choose to create two points to draw the line.
400
The scientist finds out that she can reject her null hypothesis and there is a difference between the mean weights of the two bat populations. Then she finds out her math was incorrect and this is actually a false positive, she rejected her null when she should have retained it. What type of error is this? How can we control for this type of error?
What is Type I error. We can control this by setting a small alpha like .01 or .05
400
This test takes a sample of one group of people and measures them at two different times or conditions, then corrects for reduction of variance since it uses the same people.
What is the dependent samples t-test.
400
What is the confidence level? How do you find it?
What is the probability value (1-alpha) associated with a confidence interval. It is often expressed as a percentage. For example, say , then the confidence level is equal to (1-0.05) = 0.95, i.e. a 95% confidence level.
400
True or false? A Chi-square cell must have at least 5 data points in each cell to be performed.
What is True. If the estimated data in any given cell is below 5, then there is not enough data to perform a Chi-square test.
500
If you have no correlation r=0, what is the slope of your regression line?
What is 0.
500
List the steps of hypothesis testing.
1. Claim about a population value. 2. Translate the claim into two competing hypothesis. 3. Test statistics. 4. Calculate the p-value. 5. Make a decision 6. Conclusions
500
I want to test that the incidence of fatigue is different among users of Clarinex than compared to users of a placebo. 2.1% of Clarinex users report fatigue while 1.2% of placebo users report fatigue. What type of test should I use.
What is a two-sample z-test for population proportion. Since they are testing the difference between the percentage of users reporting fatigue you can see this is a test of a proportion.
500
True or false? To calculate a Confidence Interval you take your same mean and add or subtract the margin of error.
What is true. sample mean - E < Population Mean < sample mean + E
500
What is your null hypothesis and alternative hypothesis in Chi-Square testing?
What is H0: Variable A and Variable B are independent. Ha: Variable A and Variable B are not independent.