# Multiple values in a timestamp

I am working with a time series (discrete) that has ideally 1 value per time stamp. In some cases, we are seeing multiples that have a wide range all recorded with the same time stamp.

Up to now, we had been averaging the data but have found quite a few instances of very big ranges.

Should we instead be considering the modes (sometimes there are only 2 values), should we be considering a different method? When should we consider just throwing them out? There are many missing values in this data so using previous and following values in the sequence is not ideal.

I can't recall from my previous stats what the preferred method of dealing with these values is, as I haven't come across this in some time (maybe ever, in practice). Any ideas on how to handle the situation is greatly appreciated. Resources to look up would very much help as well!

Essentially the data sometimes looks like this, where the values are separated by ";" (these are not in sequence):

 00:43:00      "78;66;81"
02:01:00      "68;74"
03:53:00      "78;86;88;95;95;111;102;97;94;95"
15:48:00      "81;120;97;58;84


Edit:

While the ideal is to have 1 per timestamp, the reason why there is more than one in some instances is the truncation at minutes by the database. However, we need to pick just one value to represent that timestamp as we don't care about the seconds details.

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Please, add more details -- the crucial thing is WHY do you have multiple values if there should be one: are these accumulated over last timestep? Coincident in output from many detectors? Something else? –  mbq Mar 2 '12 at 16:20
If the final ":00" is the seconds, which is truncated, you're saying you had 3 observations in one minute, then a gap of almost 80 minutes, then 2 observations in one minute, then a gap of over 100 minutes, then 10 observations in a minute, then a gap of over 700 minutes and then 5 observations in one minute? There has to be more structure to this problem than somewhat-irregular measurements truncated to the nearest minute. I could suggest using the median, but it seems like there's more to the story here. –  Wayne Mar 2 '12 at 18:16

(Sorry for submitting this as an answer instead of a comment, but I can't comment quite yet!)