Can someone please help me with some statistics questions i am very confused. please help answer all questions i would truly appreciate it. let me know if you have any questions. thank you

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1. which z-score is more extreme?

a) -3

b) 2.5

c) 1.5

d) -4.5

2. True or False: As the alpha level increases, the size of the critical region increases and the risk of a type 1 error increases.

3: if a researcher rejects the null hypothesis which type of decision error could the researcher have made?

a) type 1

b) type 2

c) type 1 error, if the alternative hypothesis is true

d) a type 2 error, if the null hypothesis is true

4) True or False: if betta decreases the probability of rejecting H0 (null) decreases, if H1 (alternative) is true.

5) Merry cortisol wonders if people are more interested in the morning or evening, she asks one group of people to rate their stress at both 8am and 8pm and then compare stress levels across time of day. What test should she run?

a) one sample t-test

b) one way ANOVA

c) independent samples t-test

d) dependent samples t-test

e) z-test

6) To test whether talking to unborn babies influences physical and emotional well-being, Dr. Pimple randomly assigns pregnant women into one of two conditions. For the first group, women talk daily with their bellies: and in the second group, women have no scheduled conversations. what test should Dr. Pimple run on the resulting data?

a) one way ANOVA

b independent samples t-test

c) dependent samples t-test

d) z-test

7) Regarding the F statistic in Anova, the numerator represents _______ whereas the denominator represents _____

a) random error + treatment effect ; random error only

b) random error; random error

c) random error only; random error + treatment effect

d) within group variability; between group variability

8) Which of the following is right skewed and may only take on positive values?

a) the z-distribution

b) the f-distribution

c) the t-distribution

9) the critical region for a hypothesis test consist of:

a) outcomes that have a high probability if the null hypothesis is true

b) outcomes that have a very low probability if the null hypothesis is true

c) outcomes that have a very low probability if the alternative hypothesis is true

d) outcomes that have a very low probability whether or not the null hypothesis is true

e) outcomes that have a very high probability whether or not the null hypothesis is true

10) what is the best explanation for what rejecting the null hypothesis using alpha = 0.05 actually means?

a) there is a 95% chance that the alternative hypothesis is true

b) The data strongly support the hypothesis that an observed effect in the sample data was due to sampling error alone

c) the data do not support the hypothesis that an observed effect in the sample data was due to sampling error alone

d) there is less than 5% chance that the null hypothesis is true

e) None of these choices

11) if we are taking samples from a normally distributed population the distribution of the sample means:

a) is normally distributed only if the sample is normally distributed

b) is never normally distributed

c) is normally distributed only if the sample size is greater than about 30

d) is always normally distributed

12) a negative value for a correlation indicates:

a) decreases in x tend to be accompanied by increases in Y

b) decreases in X tend to be accompanied by decreases in Y

c) a much weaker relationship than if the correlation were positive correlations can never be negative

d) a much stronger relationship than if the correlation were positive

13) A distribution of test scores is approximately normal with a mean of = 500 and a standard deviation of a = 100. What is the minimum score needed to be in the highest 10 % of the population ?

a) 371

b) 628

c) 558

d) 700

14) For a normal distribution with = 100 and a = 4 , what proportion of scores in the population have values between 96 and 104 ?

a) .68

b) .16

c) .99

d) .84

15) For the same normal distribution with = 100 and a = 4 , what proportion of " samples of size n = 4 will have means with values between 96 and 104 ?

a) 57

b) 0.95

c) 0.97

d) O68

16. A Cognitive Science researcher is interested in whether there are changes in brain activity in the prefrontal cortex , measured in blood oxygenation ( Y ) , as people perform more and more challenging statistics problems ( X ) . The sum of products for X and Y ( SP [ XY ] ) is 750 , and the sum of squares for X is 25. What is the slope of the line of best fit between Problem Difficulty and Blood Oxygenation Level ?

a) 5

b) 30

c) 136

d) .05

17. The same researcher also finds that the mean Problem Difficulty is 4 , and the mean Blood Oxygenation Level is 400. What is the intercept for the line of best fit between Problem Difficulty and Blood Oxygenation Level ?

a) 280

b) 119

c) 399.84

d) 392.5

18. The regression equation is determined by minimizing :

a) the total squared error between the X and the Y values .

b) the total squared error between the predicted Y values and the actual Y values

c) the total error between the X and Y values

d) the total error between the predicted Y values and the actual Y values

19. A set of n = 25 pairs of scores ( X and Y values ) has a Pearson correlation of r = 0.60 . How much of the variance for the Y scores is predicted ( or explained ) by the relationship with X ?

a) 0.60 or 60 %

b) Unable to be determined without more information

c) 0.40 or 40 %

d) O.36 or 36 %

e) 0.64 or 64 %

20. For a set of "population" data with N = 100 , SS = 2525. Calculate the standard deviation .

a) 25.2

b) 252.5

c) 1.5

d) 5.02

e) 1.5

For the next several questions consider this scenario :

21. A researcher is investigating whether starting elementary school later each day ( so kids get more sleep) will improve standardized test performance . A class of n = 36 third - grade children is selected to participate and each child is given a standardized achievement test at the end of the year . For the regular population of third - grade children , scores on the test form a normal distribution with mean of = 480 and a standard deviation of a = 20. The mean for the sample is 540. Assume a non directional ( two - tailed ) test . What is the null hypothesis ?

a) u treatment = 480

b) u treatment does not = 480

c) u treatment < 480

d) u treatment > 480

22. state the alternative hypothesis.

a) u treatment = 480

b) u treatment does not = 480

c) u treatment < 480

d) u treatment > 480

23. What are the critical values of z at an alpha of .05 ? That is , beyond what values will you reject the null hypothesis ? ( just report the absolute value )

a) .95

b) 1.96

c) 1.45

d) 2.33

24. Scenario : A researcher is investigating whether starting elementary school later each day ( so kids get more sleep ) will improve standardized test performance . A class of n = 36 third - grade children is selected to participate and each child is given a standardized achievement test at the end of the year . For the regular population of third - grade children , scores on the test form a normal distribution with mean of = 480 and a standard deviation of a = 20. The mean for the sample is 540. Assume a non - directional ( two - tailed ) test .

Compute the value of the appropriate test statistic for the study above using a non - directional ( two tailed ) hypothesis and a = 0.05 . Enter only the value of the test statistic in decimal form .

A) 18

b)-18

c) 3

d) 4

25. What decision should be made about the null hypothesis and the effectiveness of this study - skills program ?

Reject the null hypothesis

Fail to reject the null hypothesis

26. Construct a 95 % confidence interval on the mean . What is the upper and lower bound ?

a) Upper = 6.8 ; Lower =-6.8 b) Upper =486 ; Lower =473

c) Upper = 541 ; Lower = 539 d) Upper = 546 ; Lower = 533

27. The following data are from a study examining the effect of a treatment by measuring a group of n = 4 participants before and after they receive treatment .

[for consistency , please subtract " Before " scores from " After " scores , so the mean you obtain should be a positive value ]

Participant	Before	After
A	8	12
B	7	15
C	4	14
D	7	9

For the above data compute the appropriate test statistic

a) 5.12

b) 3.182

c) -6.6

d) 3.29

28) What is the critical value of the test statistic ?

a) 8.6

b) 3.69

c) 3.182

d) 1.45

29) Do we have evidence for an effect of treatment for two - tailed test the .05 level ?

Yes , reject the null

No , fail to reject the null

30)Scenario : Does the age at which babies learn to crawl depend on the time of the year that the babies . were born ? Data were collected from parents who brought their babies into the University of Denver's Infant Study Center to participate in one of a number of experiments between 1988 and 1991. Parents reported the birth month and the age in which their child first began to crawl . The resulting data were grouped by month of birth :

birth month	mean	std. dev.	n
january	29.84	7.08	32
may	28.58	8.07	27
september	33.83	6.93	38

crawling age is given in weeks. assume that the data can be considered as three independent random samples, one from each of the populations comprised of babies born in that particular month and that the populations of crawling ages have normal distributions.

An ANOVA F test was run on the data. The following shows a portion of the results

source	df	sum of squares	mean of squares	f-ratio
group	2	505.26
error			53.45
total	96

the DENOMINATOR degrees of freedom for the ANOVA F test is:

a)94

b)3

c)93

d)2

31. The most accurate description of the alternative hypothesis for this ANOVA F test is :

a) the mean age at which babies learn to crawl is different for all three birth months .

b) the mean age at which babies learn to crawl is highest in September .

c) the mean age at which babies learn to crawl is not the same for all three birth months .

d) the mean age at which babies learn to crawl is the same for January and May .

32. The numerical value of F is :

a) 6.3

b) 4.73

c) 9.45

d) 2.12

33. What is the critical value of F ?

a) 3.09

b) 2.84

c) 4.56

d) 6.18

34. Do you have evidence that there is a significant difference between at least one of the means for these groups ?

no

yes

35. The chairperson of a psychology department suspects that some of her faculty members are more popular with students than are others . There are three sections of introductory psychology taught by Professors Snap , Crackle , and Pop . The number or students who enroll for each is :

Snap (34) Crackle (25) Pop (10)

What statistical test should the chairperson run ?

a) Independent sample t - test

b)Chi - squared goodness of fit

c)Single sample t - test

d) Linear regression

e) Chi - Square Test of Independence

36. For a = .05 , what is the critical value for the study above ?

a) 5.99

b) 7.81

c) 2.92

d) 4.3

37. Compute the appropriate test statistic for the problem in the previous question . What is your obtained test statistic ?

a) x2 =12.78

b) t = 3.29

c) x2 = 20.62

d) t = 2.56