Standard Error Bar

I'm exploring Flex as a candidate to use for developing a web application that displays many graphs. The data displayed on the graphs are discreate values with associated stardar errors. I need to display the standard errors as an error bar - similar to how MS Excel displays error bars. Can anyone tell me if this can be done with Flex?

V,
Numbers does the best it can with the information you give it. If you ask for Error Bars, Numbers will calculate the standard deviation for the series and assign that calculation result to each of the bars in the series.
If each of your values represents some statistic that in itself is accompanied by a standard error, that's another thing, but Numbers doesn't know what the error values are unless you tell it. The way to tell Numbers what the error bar values should be in these special cases is to use Custom values.
Here's an example:
I like to use the Scatter Chart, but you will find similar controls for the bar chart.
Jerry

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Standard Error Bars in charts

I would like to know if anyone has used std. error bars (as
in statistics) in column or bar charts and how that was
accomplished. I didn't see anything about it in the flex
docs.

Frustrating that these aren't included by default, isn't
it...
I'm sure the questioner long since has solved his problem or
given up, but since I've been unable to find any solutions myself
and have had to reinvent the wheel, I'll try and point anyone else
looking in the right direction.
One way to do it is to create your own IDataRenderer (or
extend or facade an existing one). You'll want to make sure you're
passing a standard deviation as part of your series data and then
in the updateDisplayList method draw it yourself, grabbing the
deviation from the data.item. You'll need to scale it
appropriately... for instance, extend CircleItemRenderer and add an
updateDisplayList along the lines of:
override protected function
updateDisplayList(unscaledWidth:Number,
unscaledHeight:Number):void
super.updateDisplayList(unscaledWidth, unscaledHeight);
if (data.hasOwnProperty('item') &&
data.item.hasOwnProperty('deviation')) {
// figure out the scale (I'm certain there must be a more
appropriate way to do this)
var scale:Number = data.y / data.item.value;
var deviation:Number = data.item.deviation as Number;
var g:Graphics = graphics;
var stroke:IStroke= new
Stroke(0,1,1,false,'normal','square');
stroke.apply(g);
// figure out the center
var trueX:Number = unscaledWidth / 2 - .5; // otherwise
seems to be off to the side, for me
var trueY:Number = unscaledHeight / 2;
// draw the error bar
g.moveTo(trueX,-(deviation * scale) + trueY);
g.lineTo(trueX,(deviation * scale) + trueY);
g.moveTo(trueX, trueY);
// draw little T's on the end of the error bar
g.moveTo(trueX -2, -(deviation * scale) + trueY);
g.lineTo(trueX +2, -(deviation * scale) + trueY);
g.moveTo(trueX -2, (deviation * scale) + trueY);
g.lineTo(trueX +2, (deviation * scale) + trueY);
From there you should be able to futz with it to make it look
pretty.
Hope someone finds this helpful.

Error bars on column charts

I'm having a problem with inserting error bars into a graph. In the Series window I pull down the menu and select "standard error", but all my error bars are the same, no matter how many categories i have, or how variable the data are within each catergory. How do i get error bars to reflect the actual data from my spreadsheet? I've calculated the standard deviations and standard error and they are clearly different from what the graph indicates. I can't select my own standard deviation data and apply it to the chart?

Hi Jim,
I checked out your claim that the Standard Error bars don't change and I can't confirm it here. Everything seems normal. Here's my test with 20 data points, using a scatter plot for easier reading, but the result was the same...
And, here's the same function of randomized data with 53 points...
Same data with Standard Deviation...
All looks ok to me. It does require that you get the scale big enough to see the change in the error bars. I used a fixed scale for all three shots, and the data is =2+1.5*RAND().
Regards,
Jerry

Error bar problem

This must be simple, but I can't figure out how to make either a standard deviation or a standard error bar to a chart.
I place the numbers 22, 33, 44 in three adjacent cells. I highlight them and see average in the lower left area. I drag this average button to a new cell, and viola the cell says 33. I click the cell and click chart and make a bar chart and get a chart that has a bar at 33. I then click the inspector and under advanced click error bars and positive and negative. For fixed value it works fine. For standard deviation or standard error, the error bar does not exist?!! How do I use the std dev or std error buttons to generate the appropriate error bar?
I can't believe this is a bug with the program, it must be a bug with me.
Please help,
Paul

Thank-you Yvan for your continued support. I have been working on this as well and spent some time with a VERY receptive and helpful Apple specialist, Chris. Indeed, what I was looking for was a chart like Yvan posted as Graphique 6. A version I created is here (hopefully I've got this image insert working:
image: !http://picasaweb.google.com/lh/photo/HeCHRLWhs3C79ewObd_TdA?feat=directlink!
I made the error bars by using a formula to generate the standard deviation:
image: !http://picasaweb.google.com/lh/photo/FnKGk70HlsKmn38cYPYQFw?feat=directlink!
Then generated custom error bars with that cell:
image: !http://picasaweb.google.com/lh/photo/5IQm4ncUiq-Q9R8H2bb3zQ?feat=directlink!
I just discovered that Excel implements the one-click error bars identically to Numbers. It is counterintuitive (to me and my coworkers who have listened to my ranting today) that the one click standard error or standard deviation buttons would not give the standard deviation or standard error plots on the average bar, rather than on a series of bars, as if they were independent data. Here is one of countless examples of data from peer reviewed scientific literature of how this type of plot is (and IMHO should be) used:
image: !http://picasaweb.google.com/lh/photo/5IQm4ncUiq-Q9R8H2bb3zQ?feat=directlink!
One can see that some of the values are within the standard error of the other values, and some are significantly different.
But I now realize that because the implementation is the same as in Excel, it is unlikely that the feature will be changed to what I see is a more logical use of the one-click button, since we can use the custom buttons if we really want to chart differently...
I want to thank Apple and the responders to this thread for their time and patience.
Paul

Calculating Standard Error from Linest

I graphed some data as a bar chart and included positive & negative standard error bars. When I try to have the calculation of standard error in the associated data table, I find that the only function available is the standard deviation, which is related but not the same. My understanding is that the Linest function will produce an array of numbers, one of which is standard error, but I cannot figure out how that function works. How is the array produced? I tried inserting the Linest function in a cell of a table separate of my data table but it only put the number which is in the A-1 cell of the array shown in the Linest explanation and I don't understand how the rest of the array is filled out. The standard error for Y, which is what I am trying to obtain, is in cell B-4 of the array as I recall.

S,
If you open the Function Browser and select LINEST, under Usage Notes you will find a link titled "Additional Statistics". The linked content includes a map of the LINEST array. Use the INDEX function to access the element of the array that you are interested in. You may need to read the INDEX function description to know how to use it.
Jerry

Standard error of mean for column/bar graphs

Hi,
Is it possible for me to have different standard errors in a column graph? (i.e. in a graph with 2 or more columns/bar to have their individual error bars drawn out?) So far I have only been able to have a single number for both columns in the graph.
V

V,
Numbers does the best it can with the information you give it. If you ask for Error Bars, Numbers will calculate the standard deviation for the series and assign that calculation result to each of the bars in the series.
If each of your values represents some statistic that in itself is accompanied by a standard error, that's another thing, but Numbers doesn't know what the error values are unless you tell it. The way to tell Numbers what the error bar values should be in these special cases is to use Custom values.
Here's an example:
I like to use the Scatter Chart, but you will find similar controls for the bar chart.
Jerry

How can I display different error bars for each point on a scatter graph?

I have a scatter chart in Numbers and I need to add error bars to the points along both the x and y axes, however, the size of the error bars for each point need to be of different sizes. Is there a way to accomplish this or is there some kind of work around to acheieve a similar result? So far the only way I can find to add error bars only allows a standard amount for each point.

I found the answer here https://discussions.apple.com/message/16440653#16441393

Scatter Chart Error Bars Help

I'm new to using iWork for my lab reports and today, while I was plotting a scatter chart, I had to put some error bars on the points in percentage form. The value for the x-axis was 0.5% and the value for they y-axis was 1.5%, and when I tried to input these, the only thing I got was the error sound and the error bars returning to 3% and 1% respectively. Anyone know why this is happening and how i might resolve this issue? Thank you in advance.

Angelos,
I'm sure that your eyes are sharper than mine. Still, if your error bar is shorter than the radius of your symbol, you aren't going to see it. The standard symbols are roughly 4mm in diameter, based on the Numbers Rulers. Let's say you have a 100 mm tall chart, an average graphic size. A 0.5% error bar would be a maximum of 0.5 mm in length, unless you suppress the axis zero, and would be hidden behind the 4 mm dia. data symbol. Yes, you could see a 3% or 4% error bar, but I'm not sure everyone would recognize that it was an error bar and not part of the data symbol.
Regards,
Jerry

Error bars in illustrator

help!! I need to insert the standard deviation in a column graph created in illustrator...how can i do this?

Plot the upper bound and lower bound error points as data sets in a line graph and then connect the dots. Once errors bars are drawn in, remove the upper and lower bound data sets.
L

How to put std dev error bars in a chart

Page 141 of the Keynote User Guide states that error bars can be shown on plotted series data. Can anyone get this to work as expected with standard deviation bars for each plotted mean value? I spoke with an Apple Tech Rep today who supposedly knows Keynote well, but he could not get std dev error bars to display properly on a line chart.
Numbers has the same instructions as Keynote and seems to be designed to work the same way.

"Properly" means placing the error bars around the mean values for each data point in a series. In my case, the x-axis is time in minutes and the y-axis is concentration of a chemical.

Cannot define error bars for individual bars, has to be whole series

I am trying to make a simple graph that plots the mean and a standard deviation. (see picture in the link) I want to assign an individual mean values for each bar (i am able to do this), and an individual standard deviation for each bar (I cannot do this).
If I set one bar's standard deviation (custom), it also assigns the SAME standard deviation value for every bar in that series (all the green bars get the same SD value, not just the first one). I have 4 bars that I want different standard deviations assigned to (2 greens and 2 yellow = 4 different means, 4 different SDs). The standard deviations are listed in the lower table.
I can't do this. This is a fatal flaw in the software, and again, forces me to use a different application. Please tell me I'm doing something wrong! I love Numbers!
Photo:
http://web.me.com/toddknutson/errorbars2.png
Please help if you can! Thanks!
Todd

I solved my own problem!!
If you want to set different error bar values for every bar in your graph:
-choose custom error bars (positive and negative)
-then delete the placeholder value that apple provides (usually 10)
-highlight MULTIPLE values in a table (these are the values you wish to have as error bars)
-bingo!
See picture!
http://web.me.com/toddknutson/errorbars3.png

LV 2009 error bar plots suggestions

I have mentioned my mixed feelings about the new error bar plot introduced in 2009 on the info-labview list and have been asked to move this discussion to this forum.
So there it goes:
Introducing the possibility to natively display plots with error bars associated with each data point is a nice touch that brings LV one step closer to being a full-fledged data analysis and representation environment. However, the feature is limited in allowing only a single axis error bar (and on the Y axis only). This might come from NI's hardware bias (time recording of waveforms, in which the time axis does not have any "error" to it, being clock driven). Some of us use LV for a tad more than just recording waveforms and displaying them. We use complex instruments, process our data extensively, and when times come to plot a XY graph (and this is true for higher dimensionality data too), each coordinate (X, Y, etc) of each data point may be affected by a statistical or experimental uncertainty.
In this kind of situation, each data point should be represented as a center point with two orthogonal error bars (with different sizes, and possibly, as offered in the new error plot, different plus and minus error bars). In most cases, the plus and minus error bars will be identical (representing the standard deviation of the data), so it would be advantageous to have an option that allows specifying that and avoid passing twice the same array of error bars to the plot formatting VI.
Note that introducing this feature wouldautomatically bring up the request to have fitting algorithms that take this kind of dual axis error bar representation into account (which most data analysis software do nowaday).
I hope this brief suggestion will be supported by other fellow LabViewers...
X.

All,
These are great suggestions, and we always enjoy getting feedback from real-world situations where LabVIEW could help out more. I really think this should be thrown on the LabVIEW Idea Exchange. Our development team looks over all the suggestions there, and it would have much more visibility than just being posted in this thread.
Also, while you are there, be sure to vote on ideas that you like! Some of the top ideas are so obvious, you will be surprised they weren't implemented already!
Rob K
Measurements Mechanical Engineer (C-Series, USB X-Series)
National Instruments
CompactRIO Developers Guide
CompactRIO Out of the Box Video

Numbers 09 error bar size

I'm new to numbers and am trying to customise error bars on my graphs.
Is it possible to create error bars of different sizes within a graph? I am using the "standard error" setting but all of the error bars are the same size regardless of sample size.
Can I select each stack in the graph and create an error bar based on its standard error?
Thanks in advance

For custom error bars, you can choose "custom" and select the error data from your table.

Error Bars Stopped Working

I'm having trouble with custom error bars in Numbers 09. I created one scatter plot and successfully added positive and negative error bars with defined values. When I created a second scatter plot with different information, the error bars with custom values selection was grayed out. I closed and reopened the file, closed down the program, ran repair permissions through Disk Utility, and rebooted the machine. For some reason, I've suddenly lost custom error bar functionality. To make sure the issue wasn't associated with my data values, I ran the same data through Excel and was able to generate the graphs with custom error bars.
(When I say custom error bars, I'm referring to defining custom values from standard deviations)
Any body have any clues. A Google search and Discussion search hasn't yielded any results.
Thanks.

Ok, not too sure what I did to fix the problem, but the issue is now fixed. For those of you who may be experiencing the same issue, here is what I did to correct the problem. Following everything I did in my first post, I trashed the Preference plist ~/Library/Preferences/com.apple.iWork.Numbers.plist. I reopened the file and clicked on the line in the chart representing my data (don't just click the chart, you have to click on the line itself). Voila!!! I have now restored functionality.

How to calculate standard error in Numbers

How to calculate standard error in Numbers?

Urbinan,
STDEV will estimate the stardard deviation based on your sample and STDEVP will calculate the standard deviation of your entire population.
Jerry

Standard Error Bar

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