4. 10-1 Introduction

5. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Figure 10-1 Two independent populations.

6. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Assumptions

7. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known

8. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Hypothesis Tests for a Difference in Means,
Variances Known

9. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-1

10. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-1

11. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-1

12. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Choice of Sample Size
Use of Operating Characteristic Curves
Two-sided alternative:
One-sided alternative:

13. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Choice of Sample Size
Sample Size Formulas
Two-sided alternative:

14. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Choice of Sample Size
Sample Size Formulas
One-sided alternative:

15. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-3

16. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Identifying Cause and Effect
When statistical significance is observed in a randomized experiment, the experimenter can be confident in the conclusion that it was the difference in treatments that resulted in the difference in response.
That is, we can be confident that a cause-and-effect relationship has been found.

17. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Confidence Interval on a Difference in Means,
Variances Known
Definition

18. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-4

19. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Example 10-4

20. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
Choice of Sample Size

21. 10-2 Inference for a Difference in Means of Two Normal Distributions, Variances Known
One-Sided Confidence Bounds
Upper Confidence Bound
Lower Confidence Bound

22. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Hypotheses Tests for a Difference in Means, Variances Unknown
Case 1:
We wish to test:

23. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Hypotheses Tests for a Difference in Means, Variances Unknown
Case 1:
The pooled estimator of 2:

24. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Hypotheses Tests for a Difference in Means, Variances Unknown
Case 1:

25. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Definition: The Two-Sample or Pooled t-Test*

26. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-5

27. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-5

28. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-5

29. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-5

30. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Minitab Output for Example 10-5

31. Figure 10-2 Normal probability plot and comparative box plot for the catalyst yield data in Example (a) Normal probability plot, (b) Box plots.

32. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Hypotheses Tests for a Difference in Means, Variances Unknown
Case 2:
is distributed approximately as t with degrees of freedom given by

33. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Hypotheses Tests for a Difference in Means, Variances Unknown
Case 2:

34. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-6

35. Example 10-6
Figure 10-3 Normal probability plot of the arsenic concentration data from Example 10-6.

36. Example 10-6

37. Example 10-6

38. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Choice of Sample Size
Two-sided alternative:

39. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Example 10-7

40. 10-3 Inference for a Difference in Means of Two Normal Distributions, Variances Unknown
Minitab Output for Example 10-7

41. 10-3.4 Confidence Interval on the Difference in Means
Case 1:

42. 10-3.4 Confidence Interval on the Difference in Means
Case 1:
Example 10-8

43. 10-3.4 Confidence Interval on the Difference in Means
Case 1:
Example 10-8

44. 10-3.4 Confidence Interval on the Difference in Means
Case 1:
Example 10-8

45. 10-3.4 Confidence Interval on the Difference in Means
Case 1:
Example 10-8

46. 10-3.4 Confidence Interval on the Difference in Means
Case 2:
Definition

47. 10-4 Paired t-Test
A special case of the two-sample t-tests of Section 10-3 occurs when the observations on the two populations of interest are collected in pairs.
Each pair of observations, say (X1j , X2j ), is taken under homogeneous conditions, but these conditions may change from one pair to another.
The test procedure consists of analyzing the differences between hardness readings on each specimen.

48. 10-4 Paired t-Test
The Paired t-Test

49. 10-4 Paired t-Test
Example 10-9

50. 10-4 Paired t-Test
Example 10-9

51. 10-4 Paired t-Test
Example 10-9

52. 10-4 Paired t-Test
Paired Versus Unpaired Comparisons

53. 10-4 Paired t-Test
A Confidence Interval for D
Definition

54. 10-4 Paired t-Test
Example 10-10

55. 10-4 Paired t-Test
Example 10-10

56. 10-5 Inferences on the Variances of Two Normal Populations
The F Distribution
We wish to test the hypotheses:
The development of a test procedure for these hypotheses requires a new probability distribution, the F distribution.

57. 10-5 Inferences on the Variances of Two Normal Populations
The F Distribution

58. 10-5 Inferences on the Variances of Two Normal Populations
The F Distribution

59. 10-5 Inferences on the Variances of Two Normal Populations
The F Distribution
The lower-tail percentage points f-1,u, can be found as follows.

60. 10-5 Inferences on the Variances of Two Normal Populations
Hypothesis Tests on the Ratio of Two Variances

61. 10-5 Inferences on the Variances of Two Normal Populations
Hypothesis Tests on the Ratio of Two Variances

62. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-11

63. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-11

64. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-11

65. 10-5 Inferences on the Variances of Two Normal Populations
-Error and Choice of Sample Size

66. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-12

67. 10-5 Inferences on the Variances of Two Normal Populations
Confidence Interval on the Ratio of Two Variances

68. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-13

69. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-13

70. 10-5 Inferences on the Variances of Two Normal Populations
Example 10-13

71. 10-6 Inference on Two Population Proportions
Large-Sample Test for H0: p1 = p2
We wish to test the hypotheses:

72. 10-6 Inference on Two Population Proportions
Large-Sample Test for H0: p1 = p2
The following test statistic is distributed approximately as standard normal and is the basis of the test:

73. 10-6 Inference on Two Population Proportions
Large-Sample Test for H0: p1 = p2

74. 10-6 Inference on Two Population Proportions
Example 10-14

75. 10-6 Inference on Two Population Proportions
Example 10-14

76. 10-6 Inference on Two Population Proportions
Example 10-14

77. 10-6 Inference on Two Population Proportions
Minitab Output for Example 10-14

78. 10-6 Inference on Two Population Proportions
-Error and Choice of Sample Size

79. 10-6 Inference on Two Population Proportions
-Error and Choice of Sample Size

80. 10-6 Inference on Two Population Proportions
-Error and Choice of Sample Size

81. 10-6 Inference on Two Population Proportions
Confidence Interval for p1 – p2

82. 10-6 Inference on Two Population Proportions
Example 10-15

83. 10-6 Inference on Two Population Proportions
Example 10-15