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# Error bars help please!! watch

1. I got 5 set of results and did the SD, standard error and mean
Then, I had another 5 set of results and did the SD, standard error and mean
How do I do them since I was told I needed only 2 bars
2. anyone
3. were the 5 sets of results just the repeat of the same experiment or were the variable changed?
4. (Original post by Sigma5116)
were the 5 sets of results just the repeat of the same experiment or were the variable changed?
Yes, it was the repeat of the same experiment and there was another set of five results not of the same experiment
5. God - I have forgotten everything... but I would guess the mean is your actual value and the error bars are plus or minus your standard error?
6. (Original post by Hanvyj)
God - I have forgotten everything... but I would guess the mean is your actual value and the error bars are plus or minus your standard error?
Thanks. But I think it was plus or minus the standard deviation not error though. I checked on google on they used 95% confidence interval of the mean
7. (Original post by Vanny17)
Thanks. But I think it was plus or minus the standard deviation not error though. I checked on google on they used 95% confidence interval of the mean
sorry, i thought that was what standard deviation was:

"The standard error of a method of measurement or estimation is the standard deviation of the sampling distribution associated with the estimation method.[1] The term may also be used to refer to an estimate of that standard deviation, derived from a particular sample used to compute the estimate."

from a quick look at wikipedia (unless I am misunderstanding something!)
8. (Original post by Vanny17)
Yes, it was the repeat of the same experiment and there was another set of five results not of the same experiment
In which case, you will do mean, standard deviation and standard error (square root of (SD/n)) for one set and different mean, standard deviation and standard error for another. Standard error is the measure of how much the sample mean (the ones you have measured) has deviated from the population mean (the one you expect).
So standard error will be plus or minus the mean that you have calculated.

I hope that helps.
9. (Original post by Hanvyj)
sorry, i thought that was what standard deviation was:

"The standard error of a method of measurement or estimation is the standard deviation of the sampling distribution associated with the estimation method.[1] The term may also be used to refer to an estimate of that standard deviation, derived from a particular sample used to compute the estimate."

from a quick look at wikipedia (unless I am misunderstanding something!)
Theres a few definitions for standard deviation, in stats class we use standard deviation to work out the points of inflexion on a curve/distribution. However in Biology we use standard deviation as a measure of the spread of the data.

In sampling, you take samples to estimate values for the whole population. The standard error is the standard deviation of the sample. There is an equation which links the standard error of the sample to the standard deviation of the population, I think it is SE = SD/sqrt(n).

Hope that clears things up

(Original post by Sigma5116)
So standard error will be plus or minus the mean that you have calculated.
I thought standard error bars would be 2x above and below the mean?
Theres a few definitions for standard deviation, in stats class we use standard deviation to work out the points of inflexion on a curve/distribution. However in Biology we use standard deviation as a measure of the spread of the data.

In sampling, you take samples to estimate values for the whole population. The standard error is the standard deviation of the sample. There is an equation which links the standard error of the sample to the standard deviation of the population, I think it is SE = SD/sqrt(n).

Hope that clears things up

I thought standard error bars would be 2x above and below the mean?
Sorry yeah it should be 2x for 95% confidence level (or 5% significance level) because of the normal distribution curve and it probably should be SE = SD/sqrt.. I haven't really made a positive contribution here have I..
Theres a few definitions for standard deviation, in stats class we use standard deviation to work out the points of inflexion on a curve/distribution. However in Biology we use standard deviation as a measure of the spread of the data.

In sampling, you take samples to estimate values for the whole population. The standard error is the standard deviation of the sample. There is an equation which links the standard error of the sample to the standard deviation of the population, I think it is SE = SD/sqrt(n).

Hope that clears things up
Certainly did!
12. (Original post by Sigma5116)
Sorry yeah it should be 2x for 95% confidence level (or 5% significance level) because of the normal distribution curve and it probably should be SE = SD/sqrt.. I haven't really made a positive contribution here have I..
Don't worry its a bit confusing, I also get muddled up with the normal distribution and significance levels as well
13. (Original post by Sigma5116)
In which case, you will do mean, standard deviation and standard error (square root of (SD/n)) for one set and different mean, standard deviation and standard error for another. Standard error is the measure of how much the sample mean (the ones you have measured) has deviated from the population mean (the one you expect).
So standard error will be plus or minus the mean that you have calculated.

I hope that helps.

(Original post by Hanvyj)
sorry, i thought that was what standard deviation was:

&quot;The standard error of a method of measurement or estimation is the standard deviation of the sampling distribution associated with the estimation method.[1] The term may also be used to refer to an estimate of that standard deviation, derived from a particular sample used to compute the estimate.&quot;

from a quick look at wikipedia (unless I am misunderstanding something!)
Thanks.
14. Is the problem now sorted? The calculations are right. You can also get the confidence interval by
Mean + S.E.*1.96 for upper confidence interval
Mean - S.E. *1.96 for lowe confidence interval

SE = SD/sqrt(n).

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