STA 210 Lecture Notes - Lecture 3: Read All About It (Song), Numeracy, Decimal Mark
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~ Statistics Lecture #3 ~
Literacy and Human Inference
o Read All About It: BN 1.1 and 1.4
o Focused on human inference from statistical summaries
o Basic numeracy is required to asses integrity of the summaries
o Focused on:
▪ Decimal point errors
▪ Deceptive charts
▪ Competence with fractions and rates
▪ Usefulness of common benchmarks
o Inductive Inference
o The process of reasoning from the known to the unknown
o Math is more about “deductive inference.”
o A politician looking at the poll results (sample) and deciding whether she has a change in the
fall election (all voters)
o Human Inference
o An off-hand phrase taken in here to mean “inferences we make from statistical constructs
like charts, graphs, numerical summaries.”
o Think of it as how you operationalize statistical descriptions.
o Really? A College Topic?
o From an article by Ryan McCready, August 10, 2017
▪ “In this post-truth era, graphs, charts, and tables are being used to skew data or
ideas like never before.”
▪ “Misleading graphs or charts are perfect for inserting an incorrect idea into a
narrative. And that idea can spread around the world in seconds before the truth
can even get its pants on.”
▪ “All it takes is a single graph from a less than reputable source, blasted out to a list of
followers, to change a story worldwide.”
o 5 Ways Writers Use Misleading Graphs to Manipulate You
o Omitting the Baseline
▪ In most cases, the baseline for a graph is 0.
▪ But writers can skew how data is perceived by making the baseline a difference
▪ This is known as a “truncated graph.”
o Manipulating the Y-Axis
▪ Expanding or compressing the scale on a graph can make changes in data seem
more or less significant than they actually are.
o Cherry Picking Data
▪ Writers may only include certain data points on their graphs to reinforce their
▪ This can create a false impression of the data.
o Using the Wrong Graph
▪ The type of graph you use should depend on the type of data you want to visualize.
▪ Using the wrong type of graph can skew the data.
▪ Writers will sometimes use the wrong type of graph on purpose.
o Going Against Conventions
▪ Over time, we have developed standards for how data is visualizes.
▪ Flipping those conventions can make a graph confusing or misleading to readers.
o Advice from Journalist Craig Silverman
o First, journalists need to acquire the basic math skills needed to properly handle numbers
o Second, they need to develop the habit of double-checking every number and figure.