One Variable Data: Distributions and Measures of Center and Spread
Mean, median, range, standard deviation, and how data transformations affect them
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You get a histogram, dot plot, or data set. The question asks: what do the numbers tell you?
Why this matters
One-variable data questions test whether you can read graphs, calculate statistics, and reason about what happens when data changes. Students who know mean and median still get tripped up by transformation questions and grouped data estimation. Four patterns, each testing a different angle on the same data set.
The four patterns
Direct Data Interpretation
Read information straight from a graph or table. Which value is most frequent? How many fall in a range? Pure reading — no calculation.
›Measures of Center and Spread
Calculate or compare mean, median, range, or standard deviation. Know when to use each and how outliers affect them differently.
›Analysis of Data Transformations
What happens to the mean or median if you add a value, remove one, or change one? Think about direction and magnitude without recalculating everything.
›Statistical Inference
Data is grouped into intervals. You can't find exact values, so estimate the median's interval or approximate the mean from a frequency table.