Interpreting Confidence Intervals

Part 2; Interpreting Confidence Intervals (22 points)

In the table below are a list of real odds ratios or relative risks and confidence intervals found in published studies.  When interpreting results, you should consider several points about both the odds ratio (or relative risk) and the confidence interval.

Table 2: List of Odds Ratios or Relative Risks from the Literature and their 95% Confidence Intervals

Odds Ratio or Relative Risk

95% Confidence Interval

1

0.50

0.27-0.89

2

2.05

1.08-3.89

3

1.85

0.99-3.45

4

1.54

0.65-3.61

5

1.03

0.46-2.30

6

0.40

0.15-1.06

7

1.92

1.00-3.68

8

0.94

0.12-7.15

9

1.38

0.22-8.77

10

2.53

1.35-4.74

11

6.46

3.76-11.11

12

1.00

0.44-2.27

Without paying attention to the confidence intervals, for each of the 12 odds ratios or relative risks, state whether the association is indicative of a risk factor, protective factor or absolutely no association. (6 points)

Considering that any odds ratio or relative risk which is > 2.00 or < 0.50 is a strong one, for each of the 12 odds ratios or relative risks, state whether the association is a strong one, a weak one or nonexistent. (6 points)

For each of the 12 confidence intervals, state whether the association is statistically significant at the 95% level or not. (6 points)

Is there one association with borderline significance? Cite the odds ratio and confidence interval.  (2 points)

Among the 3 which are statistically significant risk factors, which odds ratio, with its confidence interval is the least precise?  Which of the 3 is probably the most precise?  (2 points)