1. Can you trust Statistics?
University of Ottawa Day Lecture by D. McDonald from the Department of Mathematics and Statistics
Can you trust Statistics?
Selling your ideas is challenging. First, you must get your listeners to agree with you in principle. Then, you must move them to action. Use the Dale Carnegie Training® Evidence – Action – Benefit formula, and you will deliver a motivational, action-oriented presentation.
Can you trust statistics?

2. In 1953: 60,000 victims of polio in the USA
In the early 1950’s Dr. Jonas Salk developed a vaccination against polio.
Before a massive vaccination program could be started it was necessary to prove the vaccine was effective.
Open your presentation with an attention-getting incident. Choose an incident your audience relates to. The incidence is the evidence that supports the action and proves the benefit. Beginning with a motivational incident prepares your audience for the action step that follows.
Can you trust statistics?

3. A Randomized, Controlled Experiment
400,000 elementary school students participated in the experiment.
200,000 chosen at random from in the treatment group got the vaccine.
The remaining 200,000 in the control group did not get the vaccine.
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Can you trust statistics?

4. A Randomized, Controlled Double-Blind Experiment
The 200,000 children in the control got a fake vaccination called a placebo.
The children and their parents were not told if they got the real vaccine or not.
Even the doctors and nurses didn’t know; only the statisticians knew
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Can you trust statistics?

5. Can you trust statistics?
Experimental Results
Size
Rate
Treatment
200,000 28
Control 71
Total
400,000 99
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Looks promising but is it significant?
Can you trust statistics?

6. Analysis: The Devil’s Advocate
Let’s play the devil’s advocate. Let’s assume the vaccine has no effect.
Then the 99 cases of polio were split into the two groups purely at random.
Is it very likely only 25 fall in the treatment group?
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Can you trust statistics?

7. Can you trust statistics?
A Probability Model
Put 400,000 balls in an urn with 99 black and the rest white.
Draw 200,000 (for the treatment group) and count the number of black balls.
What is the chance of a split as extreme or more extreme than 28 in the treatment group and 71 in the control group.
About 4 in 10 million
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Can you trust statistics?

8. Calculating Probabilities
A statistician relies on the theory of probability to calculate probabilities.
The number of black balls X in the treatment group follows the hypergeometric distribution.
Next, state the action step. Make your action step specific, clear and brief. Be sure you can visualize your audience taking the action. If you can’t, they can’t either. Be confident when you state the action step, and you will be more likely to motivate the audience to action.
Can you trust statistics?

9. Conclusion: Get vaccinated!
We must reject the hypothesis that the treatment has no effect; otherwise we must believe we are incredibly unlucky.
We can therefore recommend mass vaccination.
We also note a vaccination does not prevent polio. Your best protection is to get vaccinated and encourage everyone to be vaccinated.
To complete the Dale Carnegie Training® Evidence – Action – Benefit formula, follow the action step with the benefits to the audience. Consider their interests, needs, and preferences. Support the benefits with evidence; i.e., statistics, demonstrations, testimonials, incidents, analogies, and exhibits and you will build credibility.
Can you trust statistics?

10. Can you trust statistics?
A Statistician’s Job
Understand the problem.
Design experiments properly so something can be proved.
Use probability and computers to calculate the significance of the results.
To close, restate the action step followed by the benefits. Speak with conviction and confidence, and you will sell your ideas.
Can you trust statistics?