Confidence Intervals
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
...
Confidence Intervals
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 your place of work. 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?
Confidence intervals are an estimated range of values from a set of sample data that is likely to
include the true mean of the population [ CITATION Hol17 \l 1033 ]. Confidence intervals
provide us the upper and lower limits around the sample mean, and within the interval, we can be
confident that we captured the population mean. Most often you will see confidence intervals of
95% or 99%. The 95% confidence interval is most frequently used because as the confidence
level increases the margin of error also increases. This also widens the interval and sometimes it
can become so large that the data is useless. An example of this would be I am 99% certain that
you will score between 10 and 100 on your next exam.
Blood glucose control is something constantly measured within healthcare especially in critically
ill patients. There are various blood glucose control algorithms, confidence intervals could be
used to determine the algorithm that delivers the best glucose control within similar sample
patient groups. If in a sample group of 30 patients the mean glucose was 111 the confidence
interval for a 95% confidence level would be 102-120. The interpretation of this could mean that
95% of the patients using this glucose control algorithm can expect to have blood glucose levels
between 102-120. Analyzing data in this manner could help the facility select the most efficient
glucose control algorithm for the patients.
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