Reading Population Data
Median Age Describes a Population, Not a Typical Lifespan
Understand what median age says about a population, why it differs from life expectancy, and what an age distribution can reveal beyond one number.
CONTEXT FOR EVERYDAY CURIOSITY
Journal
Reading the Evidence
A Survey Response Rate Is Not the Same as Its Sample Size
Read survey response rates alongside sample size, eligibility and recruitment details instead of treating one percentage as a verdict on accuracy.
Reading the News
Two Trends Moving Together Do Not Yet Explain Each Other
Read a story about two changing trends by checking the timeline, possible shared causes and the evidence needed for a causal claim.
Reading the Numbers
Real and Nominal Wage Growth Answer Different Questions
Read wage-growth headlines by separating the money amount from inflation-adjusted purchasing power and checking the period and population measured.
Reading the News
An Exit Poll Surveys Voters; It Does Not Count the Ballots
Exit polls estimate patterns from surveyed voters. Learn why their numbers differ from ballot counts and why early versions can change.
Numbers in Context
An Index Starting at 100 Shows Change From a Chosen Base
Read an index set to 100 without treating its points as currency, and calculate percentage changes from the right starting value.
Numbers in Context
A Population Total and an Annual Migration Flow Count Different Things
Distinguish a population measured at a particular date from migration counted over a period before comparing headline numbers.
Reading the News
Equal Steps on a Logarithmic Chart Represent Equal Ratios
On a logarithmic chart, equally spaced marks can represent multiplication rather than addition. Read the axis before comparing slopes.
Reading Numbers
A Weighted Survey Percentage Is Not Always the Raw Share of Respondents
A worked example explains why a weighted survey percentage can differ from a raw headcount, and what methodology details a reader should check.