How can I understand my standard deviation?
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I have some (2749) senor output values. They range from 0 to 1769. With google spreadsheet I put it thru some calculations to get the (mean) average and standard deviation. With this I created two colums BINS and NORMDIST to create a chart. Please look at the attached image.
Mean is 53.35. Standard deviation is 61.23
What can I extrapolate from this?
Is one deviation 61.23, two deviation 122,46? Two deviations gives me ~95%. So since my mean is 53, 95% is a range from 0 til 122?
My chart shows while the range is from 0 to 1769, its mean is 53. Is my data bad? The form of the curve the data makes is very "typical" distribution, but a little skewed to the left?
STDEV
standard-deviation
asked Nov 26 at 9:27
fUrious
82
add a comment |
up vote
1
down vote
favorite
I have some (2749) senor output values. They range from 0 to 1769. With google spreadsheet I put it thru some calculations to get the (mean) average and standard deviation. With this I created two colums BINS and NORMDIST to create a chart. Please look at the attached image.
Mean is 53.35. Standard deviation is 61.23
What can I extrapolate from this?
Is one deviation 61.23, two deviation 122,46? Two deviations gives me ~95%. So since my mean is 53, 95% is a range from 0 til 122?
My chart shows while the range is from 0 to 1769, its mean is 53. Is my data bad? The form of the curve the data makes is very "typical" distribution, but a little skewed to the left?
STDEV
standard-deviation
asked Nov 26 at 9:27
fUrious
82
Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I have some (2749) senor output values. They range from 0 to 1769. With google spreadsheet I put it thru some calculations to get the (mean) average and standard deviation. With this I created two colums BINS and NORMDIST to create a chart. Please look at the attached image.
Mean is 53.35. Standard deviation is 61.23
What can I extrapolate from this?
Is one deviation 61.23, two deviation 122,46? Two deviations gives me ~95%. So since my mean is 53, 95% is a range from 0 til 122?
My chart shows while the range is from 0 to 1769, its mean is 53. Is my data bad? The form of the curve the data makes is very "typical" distribution, but a little skewed to the left?
STDEV
standard-deviation
asked Nov 26 at 9:27
fUrious
82
I have some (2749) senor output values. They range from 0 to 1769. With google spreadsheet I put it thru some calculations to get the (mean) average and standard deviation. With this I created two colums BINS and NORMDIST to create a chart. Please look at the attached image.
Mean is 53.35. Standard deviation is 61.23
What can I extrapolate from this?
Is one deviation 61.23, two deviation 122,46? Two deviations gives me ~95%. So since my mean is 53, 95% is a range from 0 til 122?
My chart shows while the range is from 0 to 1769, its mean is 53. Is my data bad? The form of the curve the data makes is very "typical" distribution, but a little skewed to the left?
STDEV
standard-deviation
standard-deviation
asked Nov 26 at 9:27
fUrious
82
asked Nov 26 at 9:27
fUrious
82
asked Nov 26 at 9:27
fUrious
82
asked Nov 26 at 9:27
fUrious
82
asked Nov 26 at 9:27
fUrious
82
82
Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55
add a comment |
Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55
Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55
add a comment |
1 Answer
1
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oldest
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up vote
0
down vote
accepted
- I think that you can simply ignore data beyond 3σ (usually you don't need more precise results, because you have 99+% probability that each new result will be in 3σ range from the peak of your distribution).
- Then try to repeat your calculations without "unnecessary" data (those that lay beyond 3σ). Maybe it will lead to better result.
Each experiment has its own appropriate precision. Your data can be too precise for one experiment and nearly useless for another; depends only on the kind of experiment.
answered Nov 26 at 9:56
Kelly Shepphard
2128
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
- I think that you can simply ignore data beyond 3σ (usually you don't need more precise results, because you have 99+% probability that each new result will be in 3σ range from the peak of your distribution).
- Then try to repeat your calculations without "unnecessary" data (those that lay beyond 3σ). Maybe it will lead to better result.
Each experiment has its own appropriate precision. Your data can be too precise for one experiment and nearly useless for another; depends only on the kind of experiment.
answered Nov 26 at 9:56
Kelly Shepphard
2128
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
add a comment |
up vote
0
down vote
accepted
- I think that you can simply ignore data beyond 3σ (usually you don't need more precise results, because you have 99+% probability that each new result will be in 3σ range from the peak of your distribution).
- Then try to repeat your calculations without "unnecessary" data (those that lay beyond 3σ). Maybe it will lead to better result.
Each experiment has its own appropriate precision. Your data can be too precise for one experiment and nearly useless for another; depends only on the kind of experiment.
answered Nov 26 at 9:56
Kelly Shepphard
2128
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
- I think that you can simply ignore data beyond 3σ (usually you don't need more precise results, because you have 99+% probability that each new result will be in 3σ range from the peak of your distribution).
- Then try to repeat your calculations without "unnecessary" data (those that lay beyond 3σ). Maybe it will lead to better result.
Each experiment has its own appropriate precision. Your data can be too precise for one experiment and nearly useless for another; depends only on the kind of experiment.
answered Nov 26 at 9:56
Kelly Shepphard
2128
- I think that you can simply ignore data beyond 3σ (usually you don't need more precise results, because you have 99+% probability that each new result will be in 3σ range from the peak of your distribution).
- Then try to repeat your calculations without "unnecessary" data (those that lay beyond 3σ). Maybe it will lead to better result.
Each experiment has its own appropriate precision. Your data can be too precise for one experiment and nearly useless for another; depends only on the kind of experiment.
answered Nov 26 at 9:56
Kelly Shepphard
2128
answered Nov 26 at 9:56
Kelly Shepphard
2128
answered Nov 26 at 9:56
Kelly Shepphard
2128
answered Nov 26 at 9:56
Kelly Shepphard
2128
2128
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
add a comment |
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
1σ = 61.23? With the first round of standard deviation, you mean that I can go back and redo it and ignoring data greater than 3σ (183)? I would pretty much get the same data (ish) as that way up at 1769 is just a single instance.
– fUrious
Nov 26 at 10:51
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
3σ from the peak, so it's more like 53.35+3*61.23=237. Usually, in order to have a "good" distribution, it's better to exclude those data that are beyond 237 (though you can show a bit of horizontal line, if needed) classifying them as low-probability results. After excluding, you can't anymore use excluded results anyway, so your new standard deviation will depend only on "0-237 data" (better for precision than "0-1769 data"). Probably precision will change insignificantly, as you've said, but it definitely will be better.
– Kelly Shepphard
Nov 26 at 11:37
add a comment |
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Your question is better suited for stats.stackexchange.com
– NoChance
Nov 26 at 9:49
@NoChance Thank you for your suggestion!
– fUrious
Nov 26 at 10:55