In: Statistics and Probability
Benford's Law claims that numbers chosen from very large data
files tend to have "1" as...
- Benford's Law claims that numbers chosen from very large data
files tend to have "1" as the first nonzero digit
disproportionately often. In fact, research has shown that if you
randomly draw a number from a very large data file, the probability
of getting a number with "1" as the leading digit is about 0.378.
Suppose you are an auditor for a very large corporation. The
revenue report involves millions of numbers in a large computer
file. Let us say you took a random sample of n = 258
numerical entries from the file and r = 80 of the entries
had a first nonzero digit of 1. Let p represent the
population proportion of all numbers in the corporate file that
have a first nonzero digit of 1. Test the claim that p is
less than 0.378 by using α = 0.5.
- State the null hypothesis, alternate hypothesis, and level of
significance.
- What is the z-score (show calculations)
- What is the probability that your claim is true?
- What is your conclusion?
- Find a 99% confidence interval for the probability of getting
the number “1” as the leading digit.
Show calculations.
How large a sample size should be used
to the 90% sure that the sample proportion p is within a
margin of error E = .05. Show calculations.