The alpha level that is usually used is 0.05. There are times when an alpha level that is either higher or lower can be used instead.
With a lower alpha level: You would use this in a situation where a more precise result would be needed. This would be used frequently in the medical field. Using an alpha level that is lower would help decreased the chance of error. An example of this would be using a smaller alpha level in the case of studying new Pharmeceutical drugs. You would use this when serious injury or death could result.
Example of when you would use a high alpha level: You would use a higher margin of alpha level when you have a broader topic and where having a higher chance of error is acceptable. Basically, you would use a higher alpha level if you do not really need as close accuracy as other alpha levels mentioned. An example of this would be studying all the different types of comorbidities that can affect a general population.
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