The following replicate calcium determinations on a blood sample using atomic absorption spectrophotometry (AAS) and a new colorimetric method were reported. AAS:

10.9; 10.1; 10.6; 11.2; 9.70; 10.0.

New calorimetric method: 9.20; 10.5; 9.70; 11.5; 11.6; 9.30; 10.1; 11.2.

Is there a significant difference in the precision of the two methods at 95% confidence level?

The precision of a method is being established, and the following data are obtained: 22.23.22.18, 22.25, 22.09, and 22.17%. Is 22.09% a valid measurement at the 95% confidence level?

Which of the following t-test confidence intervals indicate that there is a statistically significant difference between groups?

-15.23 to 23.12

-2.57 to -1.58

-0.05 to 5.47

-12.87 to 0.03

Which of the following confidence intervals would be associated with a p-value of 0.34, assuming an alpha of 0.05?

-2.54 to 1.38

-35.23 to -23.72

0.19 to 0.89

-15.05 to -5.47

You read a research report of the differences in weight gain in infants on enriched formula (sample 1) and soy-based formula (sample 2). The findings are reported as: t=6.79; p=.006; Confidence interval of the mean difference: 4.76 to 8.43.

What is the hypothesis decision?

Reject the null hypothesis

Accept the null hypothesis

Sample 2 is larger than sample 1: the soy-based formula showed greater weight gain in infants than the enriched formula

Sample 1 is larger than sample 2: the enriched formula showed greater weight gain in infants than the soy-based formula

You read a research report of the differences in weight gain in infants on enriched formula (sample 1) and soy-based formula (sample 2). The findings are reported as: t=6.79; p=.006; Confidence interval of the mean difference: 4.76 to 8.43.

What is the conclusion statement?

Accept the null hypothesis

Sample 2 is larger than sample 1: the soy-based formula showed greater weight gain in infants than the enriched formula

Reject the null hypothesis

Sample 1 is larger than sample 2: the enriched formula showed greater weight gain in infants than the soy-based formula

You read a research report in which the confidence interval of the mean difference is reported as -1.45 to 3.46. You know from this information that:

There is no statistically significant differences between samples

There is a statistically significant difference between samples; the mean of sample 1 is larger than the mean of sample 2

There is a statistically significant difference between samples; the mean of sample 1 is smaller than the mean of sample 2