# How to put errorbars

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Aftab Ahmed Khan on 25 Jul 2014
Answered: Abo Saqer on 15 Aug 2017
Hi Everyone, How can i put errorbars in my figure below (Between red and green graphs)? Star Strider on 25 Jul 2014
Use the errorbar function on the line of your choice. The easiest way to do this is to plot that line, then use hold to plot the others:
figure(1)
errorbar(Traffic, EngsetPb, barvector)
hold on
plot( ... the rest ... )
hold off
grid
Hypothetical variables here.

Star Strider on 25 Jul 2014
What error bars do you want to plot? The Statistics Toolbox should give you the standard errors if you are using a regression function. The functions and methods you use to get those depend on the regression function you’re using. For nlinfit for instance, you would use nlpredci.
Otherwise calculating confidence intervals is more complicated, for instance if you have empirical data you are plotting as a mean and standard error at each point. Those are usually given with respect to a specific distribution. (My experience with the Erlang distribution is limited, so I can’t comment on it specifically.) The general rule is to use either the t-distribution or the normal distibution. For the normal distribution it is usually given as 1.96 times the standard error. The standard error is given by:
SE = std(data)/sqrt(N);
where N = length(data) for each point.
Aftab Ahmed Khan on 25 Jul 2014
Awesome, Great. Done Cheers. This is what i get. Still some work left in it as the red graph should match the green graph for me. Star Strider on 25 Jul 2014
My pleasure!

Wayne King on 25 Jul 2014
Edited: Wayne King on 25 Jul 2014
Do you have the Statistics Toolbox?
x = 1:10;
y = sin(x);
e = std(y)*ones(size(x));
plot(x,y,'b')
hold on
errorbar(x,y,e,'bo','markerfacecolor',[0 0 1])
Not sure exactly what you mean by "between red and green graphs"
I'm assuming that each data point is an estimate and you have an associated confidence inteval that you want to represent

Aftab Ahmed Khan on 25 Jul 2014
Thank you for the reply. The red graph is my calculated blocking probability and i want to show the errorbar on this graph. What is mean by confidence interval? Sorry, if it is a very basic question as i am not as good when it comes to statistic.
Wayne King on 25 Jul 2014
Presumably this probability comes with some associated error, you just want to use that error in errorbar()

Abo Saqer on 15 Aug 2017
Hello
Can I get this code to calculate BP, please