Risk-And-Bias gcse Edexcel

Relative & Absolute Risks

How do I calculate the absolute risk of an event happening?

• You can use collected data to estimate the probability that an event will occur

  • If the event is something negative or undesirable

    • then the estimated probability is known as the risk (or absolute risk) of the event occurring

  • 

    • This is just the experimental probability of the ‘risky’ event occurring

    • So risk will always be a number between zero and one

  • e.g. an area in a particular town has flooded in 8 years out of the past 50 years

    • the risk of the town flooding in a given year is

• Insurance companies use risk to decide how much to charge for insurance

  • Higher risk means higher cost for the insurance

How do I calculate relative risk?

• Relative risk measure how many times more likely an event is to occur for one group, compared with another group

  • 

    • This is not a probability

    • So relative risk does not have to be between zero and one

  • e.g. the risk of having an accident is 0.025 for people who have taken a driving safety course, and 0.09 for people who have not taken the course

    • the relative risk of having an accident for people who haven’t taken the course compared with people who have taken the course is <img alt=”fraction numerator 0.09 over denominator 0.025 end fraction equals 3.6″ data-mathml=”<math ><semantics><mrow><mfrac><mrow><mn>0</mn><mo>.</mo><mn>09</mn></mrow><mrow><mn>0</mn><mo>.</mo><mn>025</mn></mrow></mfrac><mo>=</mo><mn>3</mn><mo>.</mo><mn>6</mn></mrow><annotation encoding=”application/vnd.wiris.mtweb-params+json”>{“fontFamily”:”Times New Roman”,”fontSize”:”18″,”autoformat”:true,”toolbar”:”<toolbar ref=’general’><tab ref=’general’><removeItem ref=’setColor’/><removeItem ref=’bold’/><removeItem ref=’italic’/><removeItem ref=’autoItalic’/><removeItem ref=’setUnicode’/><removeItem ref=’mtext’ /><removeItem ref=’rtl’/><removeItem ref=’forceLigature’/><removeItem ref=’setFontFamily’ /><removeItem ref=’setFontSize’/></tab></toolbar>”}</annotation></semantics></math>” height=”47″ role=”math” src=”data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20xmlns%3Awrs%3D%22http%3A%2F%2Fwww.wiris.com%2Fxml%2Fmathml-extension%22%20height%3D%2247%22%20width%3D%2290%22%20wrs%3Abaseline%3D%2230%22%3E%3C!–MathML%3A%20%3Cmath%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E.%3C%2Fmo%3E%3Cmn%3E09%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E.%3C%2Fmo%3E%3Cmn%3E025%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmo%3E.%3C%2Fmo%3E%3Cmn%3E6%3C%2Fmn%3E%3C%2Fmath%3E–%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%40font-face%7Bfont-family%3A’math1dd165a6c6b5bc8158c57065d13’%3Bsrc%3Aurl(data%3Afont%2Ftruetype%3Bcharset%3Dutf-8%3Bbase64%2CAAEAAAAMAIAAAwBAT1MvMi7iBBMAAADMAAAATmNtYXDEvmKUAAABHAAAADxjdnQgDVUNBwAAAVgAAAA6Z2x5ZoPi2VsAAAGUAAAA%2BGhlYWQQC2qxAAACjAAAADZoaGVhCGsXSAAAAsQAAAAkaG10eE2rRkcAAALoAAAADGxvY2EAHTwYAAAC9AAAABBtYXhwBT0FPgAAAwQAAAAgbmFtZaBxlY4AAAMkAAABn3Bvc3QB9wD6AAAExAAAACBwcmVwa1uragAABOQAAAAUAAADSwGQAAUAAAQABAAAAAAABAAEAAAAAAAAAQEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAgICAAAAAg1UADev96AAAD6ACWAAAAAAACAAEAAQAAABQAAwABAAAAFAAEACgAAAAGAAQAAQACAC4APf%2F%2FAAAALgA9%2F%2F%2F%2F0%2F%2FFAAEAAAAAAAAAAAFUAywAgAEAAFYAKgJYAh4BDgEsAiwAWgGAAoAAoADUAIAAAAAAAAAAKwBVAIAAqwDVAQABKwAHAAAAAgBVAAADAAOrAAMABwAAMxEhESUhESFVAqv9qwIA%2FgADq%2FxVVQMAAAEAIAAAAKAAgAADAC8YAbAEELAD1LADELAC1LADELAAPLACELABPACwBBCwA9SwAxCwAjywABCwATwwMTczFSMggICAgAACAIAA6wLVAhUAAwAHAGUYAbAIELAG1LAGELAF1LAIELAB1LABELAA1LAGELAHPLAFELAEPLABELACPLAAELADPACwCBCwBtSwBhCwB9SwBxCwAdSwARCwAtSwBhCwBTywBxCwBDywARCwADywAhCwAzwxMBMhNSEdASE1gAJV%2FasCVQHAVdVVVQABAAAAAQAA1XjOQV8PPPUAAwQA%2F%2F%2F%2F%2F9Y6E3P%2F%2F%2F%2F%2F1joTcwAA%2FyAEgAOrAAAACgACAAEAAAAAAAEAAAPo%2F2oAABdwAAD%2FtgSAAAEAAAAAAAAAAAAAAAAAAAADA1IAVQDIACADVgCAAAAAAAAAACgAAABuAAAA%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%2F)format(‘truetype’)%3Bfont-weight%3Anormal%3Bfont-style%3Anormal%3B%7D%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cline%20stroke%3D%22%23000000%22%20stroke-linecap%3D%22square%22%20stroke-width%3D%221%22%20×1%3D%222.5%22%20×2%3D%2246.5%22%20y1%3D%2223.5%22%20y2%3D%2223.5%22%2F%3E%3Ctext%20font-family%3D%22Times%20New%20Roman%22%20font-size%3D%2218%22%20text-anchor%3D%22middle%22%20x%3D%2213.5%22%20y%3D%2216%22%3E0%3C%2Ftext%3E%3Ctext%20font-family%3D%22math1dd165a6c6b5bc8158c57065d13%22%20font-s