please i need help asap... i forgot about my study guide and my exam is tomorrow...im having trouble with statistics and this study guide is my only hope

**Statistics for Criminal Justice**

EXAM Study Guide

1. Inferential statistics is the process of using _______________ data to make statements about the ________________.

2. Another way of saying this, is we use the sample statistics to estimate the population ______________.

3. The sample distribution is made up of cases, while the sampling distribution is made up of _______________.

4. How would you construct a sampling distribution?

5. The mean of the sampling distribution is what?

6. The standard deviation of the sampling distribution is what?

7. The x axis of the sampling distribution contains all possible values of the ________ ________, and the y axis contains the __________ of those values occurring.

8. When the curve is close to the x axis, this means there is a ________ probability of that sample mean occurring.

9. With larger samples, the standard deviation of the sampling distribution gets ____________.

10. As the sample size increases, the probability of getting a sample mean that is far away from the mean of the sampling distribution gets _____________.

11. As the sample size reaches ______ the sampling distribution will be approximately normal.

12. To say that a sample mean (with n= 100) lies 1.96 standard deviations above the true value of the population on the sampling distribution is also to say that the sample mean lies 1.96 _________ ________ above the true value of the population mean, and that it has a probability of occurring of __.__ .

13. We interview a random sample of Texas Inmates to find out the average sentence length.

a. The type of value we are concerned with describes the population is called a _____________.

b. The true value of the mean in the population is called ___________.

c. Explain why don’t we just find the value from part b (that one ^^).

d. The type of value we calculate with our sample is called a ____________.

e. The value of the mean in the sample is notated with the symbol ___________.

f. The sample mean is the** estimate of the true value** **of the mean** in the population, notated with the symbol ___________.

14. The alpha level is the probability we obtain a sample mean from the sampling distribution, that is __________ enough that we reject the notion that the sample value is significantly different from the true population value.

15. Another way to say this is: the alpha level corresponds to the test statistic which has a probability of occurring that is ____________ the alpha level.

16. The prison commissioner tells you that the true average length of prisoner’s sentences is 18 months, based on your data, you believe that the average sentence length is longer.

a. Your hypotheses in this case would be _________ tailed.

b. Write your null and alternate hypotheses:

i.

ii.

c. Which test would you use? T test or Z test?

d. How many degrees of freedom does the test have? (n-1)

e. With an alpha level of .05, what is the critical value for this hypothesis test?

f. What is the standard error for these data?

g. What is the test statistic value?

h. What are your conclusions regarding the hypothesis test?

i. Pretend that you knew for certain that the conclusion of your hypothesis test was wrong. What type of error did you just make?

17. The process of hypothesis testing is explicitly set up to test the null-hypothesis. What property of the sampling distribution makes this true? (Where is mue on the sampling distribution?)

18. The process of hypothesis testing is formally known as _________- ____________ ______________ _____________, or (NHST). (hint: look above)

19. When the probability of obtaining the sample mean is lower than the alpha level we _____________________ the null hypothesis.

20. Another way of saying this is: we reject the null hypothesis if the absolute value of the test statistic is greater than the _________________.

21. Another way of saying this is: we reject the null hypothesis if the test statistic lies in the _____________ ______________.

22. When we compare two sample means we are estimating how many parameters?

23. You are interested in whether length of prison sentences is different for males and females. What type of hypothesis would you use to test this statement? __________ Tailed.

24. Write out the null and alternate hypotheses:

a.

b.

25. You find 9 males and 9 females in prison and find their length of sentence. The average for males is 18 months and the average for females is 22 months. The standard deviation for males was 4 months and the standard deviation for females was 5 months. With an alpha level of .05 what are the critical values?

26. How many degrees of freedom does this estimate have?

27. What is the standard error for the test statistic? (Remember the formula uses the variance)

28. What is the test statistic for the difference?

29. Based on the test statistic what is your conclusion for the hypothesis test?

30. Assume your conclusion was actually wrong. What type of error did you just make?

31. What was the probability of that error occurring?

32. Which is worse: a type I error or type II error? Why?

33. The t-distribution is actually a family of distributions, which change based on the ___________ ____________.

34. We use the t-distribution when the sample size is smaller than _____________.

35. The t-distribution approximates the z distribution when the degrees of freedom equal _______.

36. If we reject the null, then by implication we __________ the alternate hypothesis, because the hypotheses are ____________ _____________.

37. If we fail to reject the null, then by implication we ___________________ the alternate hypothesis.

38. Do we ever reject the alternate hypothesis?

39. A type II error occurs when the researcher ____________________ a null hypothesis that is actually ________________.

40. A type I error occurs when the researcher ____________________a null hypothesis that is actually ________________

41. ______________ ______________ refers to our ability to reject the null. In other words it is the ability to guard against a type II error. When we have larger samples, larger mean differences, smaller standard errors, and larger alpha levels, this ability is stronger.

42. One tailed hypothesis tests leave the probability equal to the ______________ in one tail.

Two tailed hypothesis tests leave the probability equal to _______ the ______________ in one tail. (Hint: divide the answer from the previous question in 2).

Subject | Mathematics |

Due By (Pacific Time) | 03/11/2015 04:31 pm |

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