However, in this course you should demonstrate your understanding by always reporting the uncertainty in the Results and Discussion section. Often in the literature authors omit uncertainty in their text when it is stated elsewhere. If you have no basis for estimating uncertainty the convention in science is to assume that the uncertainty is ± 1 in the position of the last digit. You can see that the quarter is more than 24.0 and less than 25.0 mm, so you could estimate it as 24.5 ± 0.5 mm. Example: You measure the diameter of a quarter dollar coin with a millimeter ruler.Otherwise, use your judgement to estimate the uncertainty based on the limits of your measuring method.Instructions for how to get statisical values from the LINEST function are described here. Propagate the error as needed (explained below). If the measurement was derived from a linear trendline equation, then use LINEST in Excel to get the standard error values of the slope and y-intercept.Tip: Use the =STDEV or STDEV.S function in Excel.The standard deviation of replicate measurements will express the uncertainty for most values in this class. Example: "The gel had 12 lanes." The number 12 has no associated uncertainty.Example: Report 8.7 ± 0.5 μM, not 8.73 ± 0.48 μM.Įxact values do not require uncertainty, unless of course the quantity was measured by some estimating method.Your value may not have precision beyond your uncertainty. Round your uncertainty to one significant digit. Appendix A: Data Presentation Measured ValuesĪll measured values must include an uncertainty, appropriate significant digits, and units.
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