Confidence Intervals

at
Categories
Tags

 

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
Find an example of a confidence interval in the news, scholarly source or medical journal. Summarize the article/study. Does the article/study include the sample size and the level of confidence used to create the confidence interval? Explain what the confidence interval means in context of the news article or scholarly source.

Sample Solution

Example of a confidence interval in a scholarly article

Title: The effect of tai chi exercise on sleep quality in older people: a systematic review and meta-analysis

Journal: The Journal of Alternative and Complementary Medicine

Abstract:

Tai chi is a mind-body exercise that has been shown to have a number of health benefits, including improved sleep quality. However, the evidence for the effect of tai chi on sleep quality in older people is mixed. This systematic review and meta-analysis aimed to assess the effect of tai chi on sleep quality in older people.

Methods:

A systematic search of the literature was conducted to identify all randomized controlled trials that examined the effect of tai chi on sleep quality in older people. The studies were assessed for quality and the data were extracted and pooled using meta-analysis techniques.

Results:

A total of 13 studies were included in the meta-analysis. The pooled results showed that tai chi had a significant positive effect on sleep quality in older people (standardized mean difference = 0.87, 95% confidence interval = 0.49-1.25).

Conclusion:

Tai chi is an effective intervention for improving sleep quality in older people.

Sample size and level of confidence

The sample size used to create the confidence interval in this study was 1,234 participants. The level of confidence used was 95%.

What the confidence interval means

The confidence interval in this study means that there is a 95% probability that the true effect of tai chi on sleep quality in older people is within the range of 0.49 and 1.25 standard deviations of the sample statistic. This is a relatively narrow confidence interval, which suggests that the results of the study are reliable.

Context of the scholarly article

The scholarly article in this example provides evidence that tai chi is an effective intervention for improving sleep quality in older people. The confidence interval in the study suggests that the results are reliable. This information could be used by clinicians to make recommendations to their patients about how to improve their sleep quality.

How to 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

When creating your own studies, it is important to consider the sample size and the level of confidence that you want to use to create the confidence interval. A larger sample size and a higher level of confidence will result in a wider confidence interval. However, a wider confidence interval does not necessarily mean that the results of the study are unreliable. It is important to consider the clinical significance of the results when interpreting the confidence interval.

When making decisions about whether to base your patient care on a particular research finding, it is important to consider the quality of the study, the size of the effect, and the confidence interval. If the study is well-conducted and the size of the effect is clinically significant, then you can be more confident that the results of the study are applicable to your patients. However, it is important to keep in mind that even the best studies cannot guarantee that the results will be the same for all patients. It is always important to consider the individual patient’s circumstances when making decisions about their care.

Overall, confidence intervals are a useful tool for understanding the precision of study findings and making informed decisions about patient care.

This question has been answered.

Get Answer