Institute:Office of National Coordinator (ONC) Workforce Training Curriculum
Component:The Culture of Health Care
Unit:Evidence-Based Practice
Lecture:Phrasing the clinical question
Harm and prognosis
Slide content:Diagnostic (Un)Certainty Can Be Expressed as Probabilities Probability is expressed from 0.0 to 1.0 Probability of heads on a coin flip = 0.5 Alternative expression is odds Odds = Probability of event occurring / Probability of event not occurring Odds of heads on a coin flip = 0.5/0.5 = 1 Rolling a die Probability of any number = 1/6 Odds of any number = 1/5 5
Slide notes:5 When we talk about diagnosis, we usually talk about the certainty or perhaps the uncertainty of the diagnosis. We typically express certainty or uncertainty as a mathematical probability, which can sometimes seem dauntingparticularly to those who have not been exposed to probability or diagnostic decision making. When we talk about probabilities, we talk about them on a scale from zero to one, which corresponds to the scale of zero percent to one-hundred percent. For example, when we flip a coin, the probability of getting heads is point five, or fifty percent. The same is true for the probability of getting tails if its a fair coin. An alternative expression of probabilities is to talk about the odds . The odds are the probability of an event occurring versus the probability of an event not occurring, or the ratio. The odds of getting heads on a coin flip is 1:1 [one to one] one is another way to say it. When we roll a single die with six possibilities on the sides of the die, the probability of getting any number is one-sixth; the odds of getting any number are one to five.