This statement needs to include the comparison, calculation, and context. This statement needs to include the comparison, calculation, and context. Comparison At is core, an experiment involves comparing at least one condition or element to another condition or element. For example, an experiment may compare the growth rate of cattle fed a specific nutritional supplement to that of cattle who received no such supplement. Another experiment might compare the duration of influenza symptoms in people who took a newly developed drug compared to the duration of symptoms in people who took an existing drug already approved for influenza. Or an experiment may compare lab writing performance of students who received instruction in writing about data with those of students who received no such instruction. In any of the above cases, only reporting the results for one of the experimental conditions without comparing it to the results of the other experimental condition provides limited information and few if any conclusions can be drawn. Calculation When numerical data is involved (growth rate, duration of symptoms, mean lab report scores), a quantitative relationship between the two data sets should be expressed. This quantitative relationship should include magnitude (how much) and direction (more than, less than). This quantitative statement is derived from a mathematical calculation. Common ways to express quantitative comparisons include "-fold difference" (i.e. half