What is the most commonly agreed upon p-value or alpha level?

What is the most commonly agreed upon p-value or alpha level?

• A. 1%
• B. 0.5%
• C. 10%
• D. 5%

Answer: (D)

In hypothesis testing, alpha is the pre-set threshold for calling something statistically significant—it represents the probability of a false positive if the null hypothesis is true. The most commonly agreed-upon value is five percent. This default balance keeps false positives relatively rare while not being so strict that real effects are routinely missed. The five-percent standard became widespread because it was practical and convenient, aligning with early statistical practices and journals’ habits. When a study’s p-value is at or below 0.05, results are typically deemed significant under this default; if it’s above, they are not. Other levels like 1% or 0.5% are used for stricter controls, and 10% can be chosen for more exploratory work, but five percent is the default you’ll see across many fields.

In hypothesis testing, alpha is the pre-set threshold for calling something statistically significant—it represents the probability of a false positive if the null hypothesis is true. The most commonly agreed-upon value is five percent. This default balance keeps false positives relatively rare while not being so strict that real effects are routinely missed. The five-percent standard became widespread because it was practical and convenient, aligning with early statistical practices and journals’ habits. When a study’s p-value is at or below 0.05, results are typically deemed significant under this default; if it’s above, they are not. Other levels like 1% or 0.5% are used for stricter controls, and 10% can be chosen for more exploratory work, but five percent is the default you’ll see across many fields.