You must write down the value and clearly indicate that you think it is an outlier and explain why you are excluding it from any further numerical analysis of your results.

Only write it down if it is within 10% of all your other values, otherwise do not record the result as it is too different to be of any importance and will distort any numerical analysis of your results.

Only write it down if it is within 50% of all your other values, otherwise do not record the result as it is too different to be of any importance and will distort any numerical analysis of your results.

You must write down the value and clearly indicate that you think it is an outlier, however, you must include it in all further numerical analysis of your results.

Do not write it down, as it will only confuse someone who reads your logbook and is not needed in any further numerical analysis of your results.