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21 . In a sample of 25 cases, two variables have a correlation of 0.45. Do a t -test to see if this result is significant at the α = 0.05 level. Use the formula:
t = r n 2 1 r 2

12.7: prediction

Use the following information to answer the next two exercises. A study relating the grams of potassium ( Y ) to the grams of fiber ( X ) per serving in enriched flour products (bread, rolls, etc.) produced the equation:
y ^ = 25 + 16 x

22 . For a product with five grams of fiber per serving, what are the expected grams of potassium per serving?

23 . Comparing two products, one with three grams of fiber per serving and one with six grams of fiber per serving, what is the expected difference in grams of potassium per serving?

12.8: outliers

24 . In the context of regression analysis, what is the definition of an outlier, and what is a rule of thumb to evaluate if a given value in a data set is an outlier?

25 . In the context of regression analysis, what is the definition of an influential point, and how does an influential point differ from an outlier?

26 . The least squares regression line for a data set is y ^ = 5 + 0.3 x and the standard deviation of the residuals is 0.4. Does a case with the values x = 2, y = 6.2 qualify as an outlier?

27 . The least squares regression line for a data set is y ^ = 2.3 0.1 x and the standard deviation of the residuals is 0.13. Does a case with the values x = 4.1, y = 2.34 qualify as an outlier?

13.1: one-way anova

28 . What are the five basic assumptions to be met if you want to do a one-way ANOVA?

29 . You are conducting a one-way ANOVA comparing the effectiveness of four drugs in lowering blood pressure in hypertensive patients. What are the null and alternative hypotheses for this study?

30 . What is the primary difference between the independent samples t -test and one-way ANOVA?

31 . You are comparing the results of three methods of teaching geometry to high school students. The final exam scores X 1 , X 2 , X 3 , for the samples taught by the different methods have the following distributions:
X 1 ~ N (85, 3.6)
X 1 ~ N (82, 4.8)
X 1 ~ N (79, 2.9)
Each sample includes 100 students, and the final exam scores have a range of 0–100. Assuming the samples are independent and randomly selected, have the requirements for conducting a one-way ANOVA been met? Explain why or why not for each assumption.

32 . You conduct a study comparing the effectiveness of four types of fertilizer to increase crop yield on wheat farms. When examining the sample results, you find that two of the samples have an approximately normal distribution, and two have an approximately uniform distribution. Is this a violation of the assumptions for conducting a one-way ANOVA?

13.2: the F Distribution

Use the following information to answer the next seven exercises. You are conducting a study of three types of feed supplements for cattle to test their effectiveness in producing weight gain among calves whose feed includes one of the supplements. You have four groups of 30 calves (one is a control group receiving the usual feed, but no supplement). You will conduct a one-way ANOVA after one year to see if there are difference in the mean weight for the four groups.

Questions & Answers

how they find mean population
Joy Reply
parts of statistics
Edwin Reply
what is a mean?
Onele Reply
given the sequence 128,64,32 find the 12th term of the sequence
Shehu Reply
12th number is 0.0625
Thangarajan
why do we use summation notation to represent set of observations
MICHAEL Reply
what is the potential outlier ?
Anik Reply
A pharmaceutical company claims that their pain reliever capsule is 70% effective. But a clinical test on this capsule showed 65 out of 100 effectiveness
jelly Reply
Part of statistics
charls Reply
how to find mean population
Dawit Reply
what is data value
Ravneet Reply
what is relative frequency
Adeyemi Reply
liner regression analysis
Swathy Reply
Proper definition of outlier?
Sumbal Reply
Extraordinary observation (too distant, high, low etc)
Petr Reply
What is outlier?
Sumbal Reply

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Source:  OpenStax, Introductory statistics. OpenStax CNX. May 06, 2016 Download for free at http://legacy.cnx.org/content/col11562/1.18
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