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Strange questions from a nitpicker ... ;p

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  • 0 0x01AA

    Simply measurements 1...N. No restrictions. The question is: If I have only one measurement, should I display 1.) A mean Value? 2.) A Standard Deviation (which would be 0 for one measurement) Thanks

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    Daniel Pfeffer
    wrote on last edited by
    #13

    The Mean is defined for N = 1, therefore it should be displayed. The Corrected Standard Deviation is not defined for N = 1. It is defined as: xavg = sum(xi)/N xstdev = sqrt(sum((xi-xavg)2)/(N-1)) The formula for Standard Deviation with N is used when one is calculating the Standard deviation of an entire population, not just of a sample. I hope you've been out-nitpicked. :)

    Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

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    • D Daniel Pfeffer

      The Mean is defined for N = 1, therefore it should be displayed. The Corrected Standard Deviation is not defined for N = 1. It is defined as: xavg = sum(xi)/N xstdev = sqrt(sum((xi-xavg)2)/(N-1)) The formula for Standard Deviation with N is used when one is calculating the Standard deviation of an entire population, not just of a sample. I hope you've been out-nitpicked. :)

      Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

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      0x01AA
      wrote on last edited by
      #14

      Thank you very much for this. Still for me, mean for N= 1 makes no sense, resp. more: has no information

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      • 0 0x01AA

        I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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        MarkTJohnson
        wrote on last edited by
        #15

        a and b are easy like you said, just display the value of the single measurement. c now, how about a message like "Not applicable, only one measurement recorded." You don't show blank and you explain why they aren't getting a value.

        I’ve given up trying to be calm. However, I am open to feeling slightly less agitated. I’m begging you for the benefit of everyone, don’t be STUPID.

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        • 0 0x01AA

          I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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          Lost User
          wrote on last edited by
          #16

          Value has no meaning without time. 1) Never had a value. 2) last value at xx:xx:xx 3) etc. Transparency and visibility lets me sleep at night. (Also ... an early warning system for the attendant).

          "Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I

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          • 0 0x01AA

            I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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            B Offline
            BernardIE5317
            wrote on last edited by
            #17

            Perhaps it will be helpful to the users to see displayed the number of said measurements.

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            • 0 0x01AA

              I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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              CPallini
              wrote on last edited by
              #18

              I see two alternative approaches

              • Always show current measurement value, but show statistical values only when statistics is meaningful (you have a 'fair' number of samples).

              or

              • Always show all values, however, at first measure: show the current value, omit or show the mean value (equal to current value) and omit the standard deviation.

              my two cents.

              "In testa che avete, Signor di Ceprano?" -- Rigoletto

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              • 0 0x01AA

                I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                Harald M
                wrote on last edited by
                #19

                Mathematicians define the (so called "Arithmetic") Mean as "Sum of all values divided by Count of all values" - see e.g. Arithmetic mean - Wikipedia[^]. Thus, the mathematically defined (Arithmetic) Mean for a single value is that single value. It does not at all matter whether you think whether this "makes sense" :-) However, did whoever gave you this specification ("need to show ... Mean Value ...") specify that he/she actually - meant you to use the arithmetic mean? (most probably yes; but asking back is not wrong - might only confuse the analyst who maybe doesn't even know that there are many other "Means"); - wanted to help the user also in such boundary cases? Maybe the analyst would even say "Oh, but for less than a handful of values that mean doesn't make any sense - there will always be 100 or 1000s of values, in practice"; then, you two should talk for some time what's the actual reason for showing those values ... That's what I think your "feeling" is about - you question the business value of showing the Mean (and Deviation) in boundary cases - which does matter. :) H.M.

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                • 0 0x01AA

                  I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                  Cpichols
                  wrote on last edited by
                  #20

                  If there is only one measurement, I would show something to indicate that measurement has begun with the opening value given and don't show any values for a, b, or c.

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                  • 0 0x01AA

                    I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                    G Offline
                    Gary Wheeler
                    wrote on last edited by
                    #21

                    Know your audience. Ask the user who will be looking at these values what they think they should see. The answers might surprise you. For example, I have an application where I don't display statistical data until a certain number of 'stable' samples have been seen. Stability is determined by a filter on the input data, which isn't useful while the process being measured is starting.

                    Software Zen: delete this;

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                    • 0 0x01AA

                      I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                      M Offline
                      maze3
                      wrote on last edited by
                      #22

                      the question for more context is that it depends. so go back to the user and ask for more clerification what is useful to them or what is the end goal of said mesaurement. a number on it's own is meaningless Someone needs to know if value is within tolerance - so current value unless said tolerance is based on a time window and so would need to be able to clearly indicate what that time window is used over the mean

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                      • 0 0x01AA

                        I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                        K Offline
                        kholsinger
                        wrote on last edited by
                        #23

                        How often do values update? Once every 0.1 second? Once per second? Minute? Hour? Day? In the first two cases, display probably doesn't matter. If user has more than a few seconds of looking at the display, then it matters. (And how big is the display? "blank" you'd have space for, but I'm guessing not a "can't display value due to insufficient data" message would be too large.

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                        • 0 0x01AA

                          I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                          Martijn Smitshoek
                          wrote on last edited by
                          #24

                          I would really like to add to your confusion. You're talking about sample count = 1 etc, but you're talking of a continuous stream of samples, have you thought about what "average" means if you have had 94760434786353845 samples accumulated over 72 hours in a changing signal, would you *seriously* want to report the average of all that? My engineering self wants to suggest that you use a sliding average window of a fixed size, say, 10, but it could be anything reasonable considering the rate of change, and any noise that you would otherwise want to average out. Then, if you pick that number, say, N=10, then you can only start reporting after you've had at least 10 samples. And that would answer your original question.

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                          • 0 0x01AA

                            I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                            BernardIE5317
                            wrote on last edited by
                            #25

                            Just wear green socks.

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                            • 0 0x01AA

                              I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                              D Offline
                              Dani6
                              wrote on last edited by
                              #26

                              Blanks can be mistaken for a missed value. I suggest a "null". A quick and thorough guide to ‘null’: what it is, and how you should use it

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                              • 0 0x01AA

                                I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                                M Offline
                                MikeCO10
                                wrote on last edited by
                                #27

                                I'd say it is an exception case that yields "Insufficient Data". One measurement is a data point. You can't infer any unbiased statistics when n=1. There is no average, mean, or SD. If you're stuck having to show a number for some reason, that's an issue. I suppose you could treat it as a null, the same as having no data.

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                                • 0 0x01AA

                                  I need to show some value for continous measurement(s): a.) Current Measurement Value b.) Mean Value of the measurements c.) Standard deviation of the measurements c.) In case there is no or only one measurement... From my point of view, I should not show any value here. Not even 0 b.) I have my doubts. The mean value is the current value. Or should I also show blank? a.) Is easy. As soon one has measured it is easy to show current valu Especally b.) drives me crazy Any suggestions/thoughts? Thank you very much in advance ;)

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                                  jschell
                                  wrote on last edited by
                                  #28

                                  For zero. Don't show anything. So don't even show the text. Either for a report or a dashboard instead of those values display "No measurements" For one, the calculated values still work. Presumably you also display a count of values.

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