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Confidence Level

What is a confidence level?

A confidence level is a measure of the likelihood that a hypothesis or prediction is accurate. It is often expressed as a percentage and indicates the degree of confidence that the prediction will hold. For example, if you have a 95% confidence level for a prediction, it means that you have a strong belief that the prediction will be accurate in 95 out of 100 instances. The confidence level is a widely used metric to quantify the certainty or reliability of findings in various fields. It is utilized in different domains in the following ways:

  • In statistics, it is used in hypothesis testing to determine the probability of the prediction holding.
  • For scientific experiments, confidence levels are used to express confidence in the output of the experiments. 
  • In surveys, the confidence level is used to determine the margin of error when sampling data from a large dataset.
  • Marketing professionals use it to determine the effectiveness of campaigns.
  • Medical and healthcare firms refer to confidence levels to determine the statistical significance of trials and the effectiveness of drugs or vaccines.
  • In the finance and economics sector, it helps assess market risk before making any financial decisions.
  • Manufacturing firms use it to ensure product quality and determine the tolerance limit for any defects.

The confidence level serves as a crucial tool across various fields, offering a benchmark for the reliability of predictions and findings.

Confidence level vs. confidence interval

It is important to note that confidence level is different from confidence interval. Here are the key differences between them.

Evaluation ParameterConfidence levelConfidence interval
DefinitionIt measures the exact value of the confidence you have in the prediction. It is the range of values that measures the confidence in the prediction.  
Representation Expressed in percentage (90%, 95%, etc.)Expressed in a range of values with lower and upper values. (80-90, 90-100, etc.)
PurposeGives you a measure of confidence in the predictionProvides the uncertainty of the prediction with the range of values.

Example of confidence level application 

An e-commerce website performed an A/B test to determine the impact of changing the color of the “Buy Now” button from green to red on the conversion rate. The visitors were randomly assigned to either the control group (green button) or the experimental group (red button). 

After collecting data on visitor behavior and purchases, the marketing team performed statistical analysis. They used the industry benchmark of a 95% confidence level to make their conclusions (The confidence level of 95% means that if the P-value of the test is below 0.05, then the test is statistically significant). The marketing team also calculated the confidence intervals for both groups. 

The analysis revealed that the p-value is below a predefined significance level (e.g., 0.05). Thus, the company confidently concluded that the color change had a statistically significant impact on the conversion rate and adopted the new design.

In this A/B test, the e-commerce website’s marketing team harnessed the power of statistical analysis, guided by a robust 95% confidence level benchmark, to unveil the true impact of altering the “Buy Now” button’s color. This data-driven approach exemplifies the importance of rigorous experimentation and quantitative analysis in shaping informed decisions that can drive business success.

Choosing a confidence level

It is crucial to select the appropriate confidence level, which may vary depending on the industry and sector. Determining the right confidence level requires considering factors such as the quality and size of the dataset, acceptable margin of error, and the required level of precision. For instance, a space science company that requires greater accuracy would need to opt for a 99% confidence interval in order to ensure the validity of its prediction. You can refer to the industry benchmark to choose a confidence level. However, industry benchmarks are just general guidelines and vary as per the conditions and requirements of the situation.


To sum up, a confidence level is a crucial measure of the likelihood that a statement or prediction is accurate. It is widely used across various fields to quantify the certainty or reliability of findings. It is important to note that the confidence level is different from the confidence interval and requires careful consideration to select the appropriate level. By harnessing the power of statistical analysis and data-driven decision-making, individuals and businesses can make informed decisions that drive success.