Calculus/Error bars

Advertisement

Expert: - 4/6/2009


Question
I'm trying to get error bars on my bar chart in Excel.

The graph is showing the mean number of eggs produced each day for a bunch of samples (X = day number, Y = eggs produced).

For the standard deviation, do I need to use the mean of the means, so to speak? This would not make sense as each bar on the chart has no relevence to the others, it's the data within each bar that is important.

If not, there would need to be a different error for each bar on the graph, even though it's the same dataset, is this possible?

Thanks.

Answer
The sample is the number of eggs each day.  

The mean is the average number of eggs each day.

If there were seven days with, say, 4, 6, 4, 2, 5, 3, and 4 egss,
the average would be (4+6+4+2+5+3+4)/7 = 28/7 = 4 eggs per day.

The variance would be sum (each day - average)^2/(n-1).

Here, the variance would be (0+4+0+4+1+1+0)/(7-1) = 10/6 = 5/3.

The standard deviation is the squareroot of the variance.
This means the st dev is √(5/3) = √15/9.

Calculus

All Answers

Answers by Expert:

Ask Experts

Volunteer

Scotto

Expertise

Any kind of calculus question you want. I also have answered some questions in Physics (mass, momentum, falling bodies), Chemistry (charge, reactions, symbols, molecules), and Biology.

Experience

Experience in the area: I have tutored students in all areas of mathematics for over 25 years. Education/Credentials: BSand MS in Mathematics from Oregon State University, where I completed sophomore course in Physics and Chemistry. I received both degrees with high honors. Awards and Honors: I have passed Actuarial tests 100, 110, and 135.

Publications
Maybe not a publication, but I have respond to well oveer 7,500 questions on the PC. Well over 2,000 of them have been in calculus.

Education/Credentials
I aquired well over 40 hours of upper division courses. This was well over the number that were required. I graduated with honors in both my BS and MS degree from Oregon State University. I was allowed to jump into a few junior level courses my sophomore year.

Awards and Honors
I have been nominated as the expert of the month several times. All of my scores right now are at least a 9.8 average (out of 10).

Past/Present Clients
My past clients have been students at OSU, students at the college in South Seattle, referals from a company, friends and aquantenances, people from my church, and people like you from all over the world.

©2012 About.com, a part of The New York Times Company. All rights reserved.