How do I denote a measurement with a margin of error using ±?

I am trying to express a quantity that is measured to be $\pu{0.75 mL}$, but could be anywhere between $\pu{0.7 mL}$ and $\pu{0.8 mL}$. Is this the correct way to do it?


$$\pu{0.75 mL} \pm \pu{0.05 mL}$$




I strongly recommend looking at this: **QUAM:2012.P1** (*EURACHEM/CITAC Guide, “**Q**uantifying **U**ncertainty in **A**nalytical **M**easurement”, 3rd Ed., 2012., 141 pages.*) You can easily [find it online](https://www.eurachem.org/index.php/publications/guides/quam), for *free*, and it is all about quantifying uncertainties in measurements, though with an obvious focus on analytical chemistry-related measurements. As an example, the figure below shows the **QUAM** recommended way to report standard and expanded uncertainties:



> 
> **9.3. Reporting standard uncertainty**
> 
> 
> **9.3.1.** When uncertainty is expressed as the combined standard uncertainty $u\_c$ (that is, as a single standard deviation), the following form is recommended:
> 
> 
> 
> > 
> > "(Result): $x$ (units) [with a] standard uncertainty of $u\_c$ (units) [where standard uncertainty is as defined in the ISO/IEC Guide to the Expression of Uncertainty in Measurement and corresponds to one standard deviation.]"
> > 
> > 
> > 
> 
> 
> NOTE: The use of the symbol $\pm$ is not recommended when using standard uncertainty as the symbol is commonly associated with intervals corresponding to high levels of confidence.
> 
> 
> Terms in parentheses [] may be omitted or abbreviated as appropriate.
> 
> 
> EXAMPLE:
> 
> 
> * Total nitrogen: $\pu{3.52 g}/\pu{100 g}$
> * Standard uncertainty: $\pu{0.07 g}/\pu{100 g}$\*
> * \*Standard uncertainty corresponds to one
>  standard deviation.
> 
> 
> **9.4. Reporting expanded uncertainty**
> 
> 
> **9.4.1.** Unless otherwise required, the result *x* should be stated together with the expanded uncertainty $U$ calculated using a coverage factor $k=2$ (or as described in section 8.3.3.). The following form is recommended:
> 
> 
> 
> > 
> > "(Result): $(x \pm U)$ (units)
> > 
> > 
> > [where] the reported uncertainty is [an expanded uncertainty as defined in the International Vocabulary of Basic and General terms in metrology, 2nd ed., ISO 1993,] calculated using a coverage factor of 2, [which gives a level of confidence of approximately 95 %]"
> > 
> > 
> > 
> 
> 
> Terms in parentheses [] may be omitted or abbreviated as appropriate. The coverage factor should, of course, be adjusted to show the value actually used.
> 
> 
> EXAMPLE:
> 
> 
> * Total nitrogen: $(3.52 \pm 0.14)~\mathrm{g}/100~\mathrm{g}$\*
> * \*The reported uncertainty is an expanded uncertainty calculated using a coverage factor of 2 which gives a level of confidence of approximately 95 %.
> 
> 
> 


This is from pages 30-31 of QUAM, referenced above. **CITAC** is the acronym for *Co-Operation on International Traceability In Analytical Chemistry*.


All that said, your notation is quite common, so no worries.


 6