Question 8.72

72. Short-term Memory. In a famous research paper in the psychology literature, George Miller found that the amount of information humans could process in short-term memory was 7 bits (pieces of information), plus or minus 2 bits.6 Let us assume that the title of Miller's paper (“The Magical Number Seven, Plus or Minus Two”) refers to a confidence interval. Assume that .

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  1. What is the point estimate for the amount of information all humans can process in short-term memory?
  2. What is the margin of error? Interpret this number.
  3. The most common confidence level in the psychological literature is 95%. Which value for is associated with 95% confidence?
  4. How large a sample size did Miller use to find the confidence interval in the title, assuming that he used 95% confidence?
  5. Suppose he had wanted the title to read “The Magical Number Seven, Plus or Minus One”? How large a sample size would he have needed?