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Confidence Intervals for Population Proportion - Excel definitions

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  • Confidence Interval
    A range of values likely to contain the true proportion, calculated using sample data and margin of error.
  • Population Proportion
    The actual fraction of a group with a certain characteristic, estimated using sample results.
  • Sample Proportion
    A value found by dividing the number of successes in a sample by the total sample size.
  • Margin of Error
    The amount added and subtracted from the sample proportion to create the confidence interval bounds.
  • Critical Value
    A number from the standard Normal distribution used to determine the margin of error for a given confidence level.
  • Z-Score
    A value indicating how many standard deviations a point is from the mean, used in confidence interval calculations.
  • Alpha
    The probability of error, found by subtracting the confidence level from one.
  • Confidence Level
    The probability that the calculated interval contains the true population proportion.
  • Sample Size
    The total number of observations or individuals included in the sample.
  • COUNTIF
    An Excel function that counts how many times a specified value appears in a dataset.
  • NORM.S.INV
    An Excel function that returns the z-score for a given left-tail probability in the standard Normal distribution.
  • Lower Bound
    The smallest value in the confidence interval, found by subtracting the margin of error from the sample proportion.
  • Upper Bound
    The largest value in the confidence interval, found by adding the margin of error to the sample proportion.
  • Statistical Inference
    The process of drawing conclusions about a population based on sample data.
  • Sampling Variability
    The natural fluctuation in sample statistics from one sample to another.