The words to use
- Percentage strength (w/v)
- Grams per 100 mL. 2% lidocaine is 2 g in 100 mL, which is 20 mg in every mL.
- Ratio strength
- 1 g in that many mL. Adrenaline 1 in 80,000 is 12.5 micrograms per mL.
- Percentage point
- The simple difference between two percentages. 28% to 41% is 13 points, but a relative rise of about 46%.
- Parts per million (ppm)
- Milligrams per kilogram. Toothpaste at 1,450 ppm contains 1.45 mg of fluoride in every gram.
- Number needed to treat (NNT)
- How many people need a treatment, over a stated time, for one to benefit: 100 ÷ the absolute risk reduction in percentage points.
