Academic Presentation
Academic Presentation #4: Explain Graphs and Uncertainty
Explain Graphs and Uncertainty
Guide the eye before you explain the result.
LESSON 04 OF 08 · READ + PRACTISEDo not display a graph and say only “You can see the result.” Tell the audience where to look and what the numbers mean. Use a simple order: orient, observe, interpret, and limit.
THE IDEA IN ONE PICTURE
Swipe across the diagram to see the full picture.
Orient: tell us what we are looking at
Name the quantity on each axis and give the units. Identify the groups. For example: “The horizontal axis shows time in minutes. The vertical axis shows temperature in degrees Celsius. The solid teal line is Design B.” If the scale is logarithmic, explain that equal steps show equal ratios, not equal differences.
Observe: describe the data first
Say “At ten minutes, Design A reached 60 degrees, while Design B reached 45.” Then interpret: “Design B stayed cooler in this test.” These numbers are invented for practice. A difference of 15 degrees Celsius is a clear comparison here. Do not casually describe Celsius temperatures as a percentage reduction: the scale has an arbitrary zero.
Limit: show what the graph cannot tell us
If you show error bars, say what they represent—for example, standard deviation or a confidence interval—and give the sample size. These describe different things. Do not claim significance only because bars do or do not overlap. A trend does not by itself prove a cause. Tell listeners what was controlled and what other explanations remain.
WATCH A REAL EXAMPLE · DATA-PRESENTATION DEMONSTRATION
Explain the graph before telling its story
Watch an academic explain a moving graph of health and income. Focus on how he guides the viewer, rather than trying to memorise the historical numbers.
Use the YouTube link if the player does not load. Turn on English captions in the player settings when available; automatic captions may contain errors.
What to notice
- 0:30–1:14: Identify the axes, bubble sizes, and colours.
- 1:47–2:19: Notice the deliberate pauses at important events.
- 3:25–3:55: Listen for the limitation of country averages.
Try it: Before the animation begins, explain what a bubble means. Then name one important limitation of the graph.
Check your viewing task
A bubble represents a country; its position shows income and life expectancy, and its size represents population. Country averages can hide differences within a country.
This is a produced BBC segment from 2010, not a current-data source or a live conference talk. You can use the same clear sequence with an ordinary static graph.
Video credit: Hans Rosling · BBC · 200 Countries, 200 Years, 4 Minutes. Source and attribution ↗
Your turn · 2-minute practice
Explain the ten-minute comparison in the figure in two sentences: one observation and one limit.
See a model answer or self-check
“At ten minutes, Design B was 15 degrees Celsius cooler than Design A. This figure alone does not show whether that difference is repeatable, because it gives no repeated measurements or uncertainty estimates.”
Explore all eight lessons
Academic Presentation · Science & Engineering · Original teaching examples. Numerical examples are illustrative, not published research results.
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