In everyday terms, a confidence interval is the range of values around a sample statistic (such as mean or
proportion) within which clinicians can expect to get the same results if they repeat the study protocol or
intervention, including measuring the same outcomes the same ways. As you ask yourself, “Will I get the
same results if I use this research?”, you must address the precision of study findings, which is
determined by the
Confidence Interval. If the CI around the sample statistic is narrow, you can be confident you will get close
to the same results if you implement the same research in your practice.
Consider the following example. Suppose that you did a systematic review of studies on the effect of tai chi
exercise on sleep quality, and you found that tai chi affected sleep quality in older people. If, according to
your study, you found the lower boundary of the CI to be .49, the study statistic to be 0.87, and the upper
boundary to be 1.25, this would mean that each end limit is 0.38 from the sample statistic, which is a
relatively narrow CI.
(UB + LB)/2 = Statistic [(1.25 + .49)/2 = .87]
Keep in mind that a mean difference of 0 indicates there is no difference; this CI does not contain 0.
Therefore, the sample statistic is statistically significant and unlikely to occur by chance.
Because this was a systematic review, and tai chi exercise has been established from the studies you
assessed as helping people sleep, based on the sample statistics and the CI, clinicians could now use your
study and confidently include tai chi exercises among possible recommendations for patients who have
difficulty sleeping.
Now you can apply your knowledge of CIs to create your own studies and make wise decisions about
whether to base your patient care on a particular research finding.
Initial Post Instructions
Thinking of the many variables tracked by hospitals and doctors’ offices, confidence intervals could be
created for population parameters (such as means or proportions) that were calculated from many of
them. Choose a topic of study that is tracked (or that you would like to see tracked) from the place you
work (must be from a hospital, this is a nursing program). Discuss the variable and parameter (mean or
proportion) you chose, and explain why you would use these to create an interval that captures the true
value of the parameter of patients with 95% confidence.
Consider the following:
How would changing the confidence interval to 90% or 99% affect the study? Which of these values (90%,
95%, or 99%) would best suit the confidence level according to the type of study chosen? How might the
study findings be presented to those in charge in an attempt to affect change at the workplace?
Sample Solution
