z-score
Deviation from mean
A z-score is a statistical measure that expresses how many standard deviations a data point lies from the mean of its distribution.
A z-score of zero indicates the value equals the mean; positive z-scores fall above the mean, negative ones below.
Z-scores allow comparison across different scales by standardizing data: Her test result had a z-score of 1.5, putting her well above average.
In research and quality control, z-scores help identify outliers and assess relative performance.
Spread around the mean
- meanAverage, or spiteful
- standardizationImplementing uniform technical specifications
- normalizationAdjusting to a standard
- formulaFixed method or notation
deviation · variance · population · sample · transformation · scale · unit · magnitude
Bell-shaped probability curve
- bell curveNormal distribution's shape
- probabilityQuantified chance of occurrence
- percentileStatistical ranking threshold
- cumulativeIncreasing by successive additions
Statistical method for evaluating claims
- significanceQuality of mattering
- p-valueProbability under null hypothesis
- confidence intervalEstimated bounds for population parameter
- researchSystematic fact-finding effort
quality control · standardized testing · SAT · IQ · growth charts · medical screening · control chart
Distant data point
- unusualNot often encountered
- typicalRepresentative of a kind
- averageArithmetic mean or ordinary
- above averageBetter than the mean
below average · rank · comparison · benchmark · how far · magnitude · direction · positive
standard deviation
Spread around the mean
- meanAverage, or spiteful
- standardizationImplementing uniform technical specifications
- normalizationAdjusting to a standard
formula · deviation · variance · population · sample · transformation · scale · unit · magnitude · difference
normal distribution
Bell-shaped probability curve
- bell curveNormal distribution's shape
- probabilityQuantified chance of occurrence
- percentileStatistical ranking threshold
hypothesis testing
Statistical method for evaluating claims
- significanceQuality of mattering
- p-valueProbability under null hypothesis
- confidence intervalEstimated bounds for population parameter
research · quality control · standardized testing · SAT · IQ · growth charts · medical screening · control chart
outlier
Distant data point
above average · below average · rank · comparison · benchmark · how far · magnitude · direction · positive · negative
- statisticsmean, median, mode, variance, standard deviation
- data processingnormalization, data entry, standardization, encoding, scaling
- growth assessmentheight, weight chart, height measurement, growth chart, growth charts
- metricsKPI, metric, KPIs, metrics, statistics
- Test Scorestest scores, percentile, percentile rank, stanine, decile
- Gaussian statisticsbell curve, normal distribution, mean, sigma, mu
z-scorepercentile
Statistical ranking threshold
percentile rank · rank · quartile · decile
z-scoreraw score
Unmodified numerical result
percentile · t-score · stanine · IQ score