Exam 7: The T Test for Independent Groups

The Food and Drug Administration wishes to determine whether the claim that Vitamin C prevents colds has any truth. In a clinical drug trial, 30 subjects were randomly assigned to either the Vitamin C group (receiving a daily supplement of the minimum daily requirement) or the placebo group (who received no supplement but did get a placebo pill). The number of self-reported colds is recorded after 3 years. Vitamin C Placebo 3 8 8 8 6 7 7 10 4 11 9 4 2 3 5 7 7 6 11 8 10 4 8 10 7 6 6 8 7 5 -The value of the numerator (either or -) in the t test formula for this problem is

A business statistician wishes to determine whether current unemployment rates differ between former communist countries and European/Asian nations that have not been under communist control. A sample of 10 countries each was randomly chosen from all eligible countries. The data are as follows: Former Communist Not Former Communist (\%) (\%) 23 12 13 8 33 9 21 14 17 7 24 8 12 10 18 11 27 12 16 7 -Are the mean percentages significantly different?

The Food and Drug Administration wishes to determine whether the claim that Vitamin C prevents colds has any truth. In a clinical drug trial, 30 subjects were randomly assigned to either the Vitamin C group (receiving a daily supplement of the minimum daily requirement) or the placebo group (who received no supplement but did get a placebo pill). The number of self-reported colds is recorded after 3 years. Vitamin C Placebo 3 8 8 8 6 7 7 10 4 11 9 4 2 3 5 7 7 6 11 8 10 4 8 10 7 6 6 8 7 5 -The degrees of freedom for this problem are

A psychiatrist is interested in the effects of a new drug for the control of depression. In a clinical trial, 18 depressed patients were randomly assigned to one of two groups, either the drug group or the placebo group. One half hour after the administration of the drug or placebo, their depression was measured by the Coolidge Axis II Inventory's Depression scale and reported as T scores (M = 50, SD = 10). Drug Placebo 52 65 53 59 58 68 50 53 53 59 58 67 55 61 66 70 53 62 -The correct statistical decision would be to

The Food and Drug Administration wishes to determine whether the claim that Vitamin C prevents colds has any truth. In a clinical drug trial, 30 subjects were randomly assigned to either the Vitamin C group (receiving a daily supplement of the minimum daily requirement) or the placebo group (who received no supplement but did get a placebo pill). The number of self-reported colds is recorded after 3 years. Vitamin C Placebo 3 8 8 8 6 7 7 10 4 11 9 4 2 3 5 7 7 6 11 8 10 4 8 10 7 6 6 8 7 5 -What significance level should be reported?

The Food and Drug Administration wishes to determine whether the claim that Vitamin C prevents colds has any truth. In a clinical drug trial, 30 subjects were randomly assigned to either the Vitamin C group (receiving a daily supplement of the minimum daily requirement) or the placebo group (who received no supplement but did get a placebo pill). The number of self-reported colds is recorded after 3 years. Vitamin C Placebo 3 8 8 8 6 7 7 10 4 11 9 4 2 3 5 7 7 6 11 8 10 4 8 10 7 6 6 8 7 5 -What can be concluded from the statistical analysis of this problem?

A business statistician wishes to determine whether current unemployment rates differ between former communist countries and European/Asian nations that have not been under communist control. A sample of 10 countries each was randomly chosen from all eligible countries. The data are as follows: Former Communist Not Former Communist (\%) (\%) 23 12 13 8 33 9 21 14 17 7 24 8 12 10 18 11 27 12 16 7 -The appropriate conclusion of this statistical analysis would be

A business statistician wishes to determine whether current unemployment rates differ between former communist countries and European/Asian nations that have not been under communist control. A sample of 10 countries each was randomly chosen from all eligible countries. The data are as follows: Former Communist Not Former Communist (\%) (\%) 23 12 13 8 33 9 21 14 17 7 24 8 12 10 18 11 27 12 16 7 -The derived t value for this problem is

A psychiatrist is interested in the effects of a new drug for the control of depression. In a clinical trial, 18 depressed patients were randomly assigned to one of two groups, either the drug group or the placebo group. One half hour after the administration of the drug or placebo, their depression was measured by the Coolidge Axis II Inventory's Depression scale and reported as T scores (M = 50, SD = 10). Drug Placebo 52 65 53 59 58 68 50 53 53 59 58 67 55 61 66 70 53 62 -The value of the numerator in the t formula for this problem (either or -) is

A psychiatrist is interested in the effects of a new drug for the control of depression. In a clinical trial, 18 depressed patients were randomly assigned to one of two groups, either the drug group or the placebo group. One half hour after the administration of the drug or placebo, their depression was measured by the Coolidge Axis II Inventory's Depression scale and reported as T scores (M = 50, SD = 10). Drug Placebo 52 65 53 59 58 68 50 53 53 59 58 67 55 61 66 70 53 62 -The degrees of freedom for this problem are

A psychiatrist is interested in the effects of a new drug for the control of depression. In a clinical trial, 18 depressed patients were randomly assigned to one of two groups, either the drug group or the placebo group. One half hour after the administration of the drug or placebo, their depression was measured by the Coolidge Axis II Inventory's Depression scale and reported as T scores (M = 50, SD = 10). Drug Placebo 52 65 53 59 58 68 50 53 53 59 58 67 55 61 66 70 53 62 -The overall results would mean that

A psychiatrist is interested in the effects of a new drug for the control of depression. In a clinical trial, 18 depressed patients were randomly assigned to one of two groups, either the drug group or the placebo group. One half hour after the administration of the drug or placebo, their depression was measured by the Coolidge Axis II Inventory's Depression scale and reported as T scores (M = 50, SD = 10). Drug Placebo 52 65 53 59 58 68 50 53 53 59 58 67 55 61 66 70 53 62 -The derived t value for this problem (either or ) is

A business statistician wishes to determine whether current unemployment rates differ between former communist countries and European/Asian nations that have not been under communist control. A sample of 10 countries each was randomly chosen from all eligible countries. The data are as follows: Former Communist Not Former Communist (\%) (\%) 23 12 13 8 33 9 21 14 17 7 24 8 12 10 18 11 27 12 16 7 -The degrees of freedom for this problem are

A business statistician wishes to determine whether current unemployment rates differ between former communist countries and European/Asian nations that have not been under communist control. A sample of 10 countries each was randomly chosen from all eligible countries. The data are as follows: Former Communist Not Former Communist (\%) (\%) 23 12 13 8 33 9 21 14 17 7 24 8 12 10 18 11 27 12 16 7 -The correct statistical decision would be

The Food and Drug Administration wishes to determine whether the claim that Vitamin C prevents colds has any truth. In a clinical drug trial, 30 subjects were randomly assigned to either the Vitamin C group (receiving a daily supplement of the minimum daily requirement) or the placebo group (who received no supplement but did get a placebo pill). The number of self-reported colds is recorded after 3 years. Vitamin C Placebo 3 8 8 8 6 7 7 10 4 11 9 4 2 3 5 7 7 6 11 8 10 4 8 10 7 6 6 8 7 5 -The derived t value (either + or -) for this problem is