"Random variable" vs. "random value" (when translating from Russian into English) In the introductory part of a Russian document I was translating, there was a simplified description of a control chart-based quality management system. 
The description contained this sentence in Russian:

Контрольные границы определяют предел ожидаемых изменений процесса, когда действуют наиболее типичные для этого процесса факторы. Наносятся контрольные границы, как правило, на расстоянии трех стандартных отклонений случайной величины от линии средних значений.

I translated the Russian sentence this way:

Variations observed within the chosen control limits are considered natural for the process, arising from typical factors that influence the process. Control limits are usually set at a distance of 3 standard deviations ("sigma") from the mean line of the random variable.

The reviewer changed it to:

Control limits are usually set at a range of 3 standard deviations from the mean line of the random value.

Which is better?
I believe it is random variable, because we are talking about Shewhart charts here, and as far as I understand, statisticians use this term, "random variable". The original Russian phrase is "random value", but I thought it was better not to follow the original too closely.  
 A: The correct phrase in order to make statistical sense, is "random variable". And this is because it refers to the "mean line" - and random values do not have a mean, only random variables do.  
If the Russian word is "value", and even if the Russian author meant "value", (s)he was simply mistaken.
Alternatively, one could consider writing "...mean line of the random values" - plural,  since probably here the theoretical expected value is unknown, and so "the mean line" is the sample mean of the observed values.
A: I side with your editor. You plot the obtained values on the plot, then draw a mean (average) line, then calculate three standard deviations above and below the line to show the boundaries. There's really no modeling involved here, hence, there's no random variable defined explicitly. You could argue that implicitly the variables are introduced, of course, but I'd go with your editor's choice to de-emphasize modeling at this stage.
Here's the original page with a chart.
If you read the whole text they consistently use terms значение (величина) that stand for value or quantity, in my opinion, to emphasize the phenomenological nature of the approach. There's very little of statistical content in the paper. All they do is to watch control boundary breaches to detect stochastic controllability as they define it. I'd definitely stick with value here. 

UPDATE: The link I gave was just one example how this paragraph is copied in Russian from one text to another. Google will spit you out dozens of example such as this one from medical field. There must be the original text from which this is copied, I suspect it's Russian translation of Chambers Wheeler book Understanding Statistical Process control. So, the precise answer would be to locate the English original in this (or other?) book.
UPDATE 2:
I don't the have the original English text from translation of which the Russian paragraph was copied, but here's a control chart description on NIST web site. Notice how they never use the term "variable". Consistent with my answer they use "measurement", "value" and "data point".
