Which of the following is a commonly accepted level for alpha risk?

Question

Options

• A0.05
• B0.50
• C0.70
• D0.95

• A
  2% (1)
• B
  90% (37)
• C
  5% (2)
• D
  2% (1)

Explanation

Note: There appears to be an error in this question. The stated correct answer (B: 0.50) contradicts established statistical practice. The actual correct answer is A: 0.05.

A 0.05 (5%) alpha level is the most widely accepted threshold for alpha risk (Type I error - the probability of falsely rejecting a true null hypothesis). It represents a balance between being too lenient and too strict when drawing conclusions from data.

Why the distractors are wrong:

• B (0.50) - A 50% chance of a false positive would be statistically meaningless; you'd essentially be flipping a coin.
• C (0.70) - Far too high; this would make false positives the norm rather than the exception.
• D (0.95) - This is a common confidence level, not an alpha level. Alpha = 1 − confidence level, so 0.95 confidence corresponds to α = 0.05, not α = 0.95.

Memory tip: Think "5% chance to mess up" - alpha of 0.05 is the industry-standard tolerance for being wrong when you claim something is statistically significant. If you see 0.95, that's the confidence, not the alpha.

I'd recommend verifying the answer key for this question, as B (0.50) is incorrect. If this is from a specific exam prep source, it may be a typo where "B" was listed instead of "A."

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