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How to Master Descriptive Statistics: 108 Flashcards on Mean, Median, Mode and Standard Deviation

Learn descriptive statistics with 108 flashcards: mean, median, mode, variance, standard deviation, z-scores, IQR, skewness and Pearson correlation.

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The mean tells you where a dataset sits. The standard deviation tells you whether that number means anything at all. Descriptive Statistics: Mean, Median, Mode & Standard Deviation (code IN3111, 108 cards) on Flip It drills the definitions, formulas and symbols that AP Statistics, intro stats and data-analysis courses assume you already know cold.

Study this deck: Descriptive Statistics: Mean, Median, Mode & Standard Deviation

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Descriptive statistics

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A sample of what the cards ask:

FrontBack
Sample standard deviation formulas = √[Σ(x − x̄)² / (n−1)], using Bessel's correction (n−1) for unbiased estimation
Why use (n−1) instead of n in sample standard deviation?Bessel's correction provides an unbiased estimate of the population variance from a sample
Interquartile range (IQR)IQR = Q3 − Q1, the range of the middle 50% of data, robust to outliers
Z-score (standard score)z = (x − μ)/σ, the number of standard deviations a value is from the mean
Chebyshev's inequalityAt least (1 − 1/k²) of data lies within k standard deviations of the mean, for any distribution
Coefficient of variationCV = (σ/μ) × 100%, the ratio of standard deviation to mean, useful for comparing variability across different scales
Common rule for identifying outliersValues below Q1 − 1.5×IQR or above Q3 + 1.5×IQR
Standard error of the meanSEM = σ/√n, the standard deviation of the sampling distribution of the mean
Positive skewnessWhen the tail on the right side is longer (mean > median)
Leptokurtic kurtosisHeavy tails and a sharp peak (high kurtosis)

The 108 cards in one glance

  • Centre: arithmetic mean, median, mode, weighted mean, geometric mean, harmonic mean, truncated mean, mid-range, root mean square, the AM ≥ GM ≥ HM inequality, multimodal datasets.
  • Spread: range, population and sample variance, both standard deviation formulas, mean absolute deviation, IQR, quartiles Q1–Q3, percentiles, coefficient of variation.
  • Shape: skewness (right and left), kurtosis (leptokurtic, platykurtic, mesokurtic), the normal distribution, the empirical 68-95-99.7 rule, log transformation of skewed data.
  • Position and standardisation: z-scores, five-number summary, outlier rules, Chebyshev's bounds at k = 2 (75%) and k = 3 (89%).
  • Relationships: covariance, Pearson's r, Spearman's rho, r = +1 / −1 / 0, correlation versus causation, contingency tables, bivariate and multivariate analysis.
  • Vocabulary and notation: population versus sample, μ and σ against x̄ and s, sampling error, standard error, frequency and cumulative frequency, relative frequency, EDA.
  • Graphs: histogram, bar chart (and the difference), box plot, stem-and-leaf display, scatterplot, pie chart.

Two things worth doing while you review

Keep the μ/σ and x̄/s cards side by side. Roughly a fifth of the deck exists only because population and sample formulas differ. Every time a variance or standard deviation card comes up, say out loud whether you are dividing by N or by n−1 before flipping. Exam questions rarely test the arithmetic — they test whether you noticed the word sample.

Pair the empirical rule with Chebyshev. The cards give 68/95/99.7 for normal data and 75%/89% for any distribution. Learn them as a matched pair: if the question mentions a bell curve, use the first set; if it says nothing about shape, only Chebyshev's weaker bound is defensible.

Sign in at flip-it.app and search the library for deck IN3111. If you want the visual side of data next, try Pandas Essentials, which puts these same summaries into code.

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