# Probability and Risk

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• Created by: Holly
• Created on: 24-10-13 18:33
• Probability and Risk
• What is risk?
• 'The probability of occurrence of some unwanted event or outcome'
• Used to multiply the likelihood by the severity to give a risk rating
• Working out probabilities
• Risk probability has a time period
• Fraction, can be turned into a percentage
• e.g: In a class, 6 pupils out of 30 got headlice in a year, so 1 in 5 or 20% risk of getting headlice in a year.
• Perceived Risk
• Over and underestimating risk
• We overestimate risk if it is:
• Involuntary (out of our control)
• not natural
• unfamiliar
• unfair
• very small
• We underestimate risk if:
• it has an effect in the long-term e.g: smoking, excessive drinking, drugs
• Based on factors such as interest and approval of the activity, not mathematical
• If data is lacking, we say the risk is uncertain
• Different types of risk factor
• Hereditary
• Physical environment
• Social environment
• Lifestyle and behaviour choices
• Correlation and causation
• Correlation
• Positive correlation is seen when an increase in one variable causes an increase in the accompanying one
• e.g: number of cigarettes smoked in a lifetime and the chances of developing cardiovascular disease
• Negative correlation seen when the value of one variable increases whilst the other decreases
• Just because there is a correlation, doesn't mean there is a direct causation