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Ch. 6 - Confidence Intervals
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Non è quello che usi tu?Cambia libro di testo
Capitolo 6, Problema 6.1.29

In Exercises 29–32, determine the minimum sample size n needed to estimate for the values of c, σ, and E.
c = 0.90, σ = 6.8, E = 1.

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Identify the formula for determining the minimum sample size n for estimating a population mean: n = (zc⋅σE)2, where zc is the critical z-value, σ is the population standard deviation, and E is the margin of error.
Determine the critical z-value (zc) for the given confidence level c = 0.90. Use a z-table or statistical software to find the z-value corresponding to the middle 90% of the standard normal distribution.
Substitute the given values into the formula: σ = 6.8 and E = 1. Replace zc with the critical z-value obtained in the previous step.
Simplify the fraction zc⋅σE by multiplying zc and σ, then dividing by E.
Square the result of the fraction to compute the minimum sample size n. If n is not a whole number, always round up to the nearest integer, as sample size must be an integer.

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Sample Size Determination

Sample size determination is the process of calculating the number of observations or replicates needed in a statistical study to ensure that the results are reliable and valid. It is crucial for achieving a desired level of confidence and margin of error in estimates. The formula often used involves the population standard deviation, the desired confidence level, and the margin of error.
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Coefficient of Determination

Confidence Level (c)

The confidence level represents the probability that the confidence interval will contain the true population parameter. A confidence level of 0.90 indicates that there is a 90% chance that the interval estimate will capture the true value. This level influences the width of the confidence interval and, consequently, the required sample size.
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Introduction to Confidence Intervals

Margin of Error (E)

The margin of error is the range within which the true population parameter is expected to lie, given a certain confidence level. It quantifies the uncertainty associated with sample estimates. A smaller margin of error requires a larger sample size, as it indicates a desire for more precise estimates of the population parameter.
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Introduction to Confidence Intervals
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