×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Percent of units experiencing conditions

Percent of units experiencing conditions

Percent of units experiencing conditions

(OP)
Hello, I could use some help estimating the percentile of units experiencing mulitiple conditions.

A product can be installed in a wide range of environments. These effect the temperature of the product. There are three variables that have the biggest impact:
T = Room temperature
D = Distance to a local obstruction
H = Heat from a nearby product

For any given set of conditoins (T, B or H) we can calculate the resulting product temperature. Also for any condition (T, B or H) we can estimate percentile of products above/below that value. For example, a 21C room is at the 50th percentile, 30C room is at the 84th percentile, etc.

I would like to combine this info in a meaningful way. For example, we have several scenarios for T, D and H. How can I calculate the percentage of units that will experience each scenario? Or better, the number of units that will experience a certain temperature level?


RE: Percent of units experiencing conditions

What is the formula you are using to calculate the resulting product temperature? Are you looking for a spreadsheet solution?

RE: Percent of units experiencing conditions

(OP)
I plotted test data on temperature vs T, D and H and correlated each set to a best-fit curve formula.

RE: Percent of units experiencing conditions

Well, take the simplest case. Suppose you have 2 subsets of each condition, i.e. T1, T2, D1, D2, H1 and H2. You have 2^3 distinct combinations to look at. For each condition, you have a weighting function that tells you probabilities for that condition, call them t1, t2, d1, d2, h1, h2. Doesn't matter what they look like, just that they are self-consistent numerical values, but ideally they should sum to 1.0

For condition T1-D1-H1, you would find the probability of that combination (lets call it P111) by mulitplying: t1 x d1 x h1

Etc. for remainining combinations.

It should work out that the sum of all combinations = 1.0

But it might not due to rounding errors, or if you didn't get the original weighting functions to sum to 1.0 for whatever reason...so I would just renormalize that sum to 1.0, i.e. figure out a factor to multiply it that gets the sum back to 1.0; then each individual combination value P111 could be multiplied by the normalization factor to get you to the final answer.

RE: Percent of units experiencing conditions

Sorry, forgot to add: the above can be generalized to any number/variety of combinations i.e. 3 T's, 4 D's and 2 H conditions.

RE: Percent of units experiencing conditions

Well...this sounds like a fun spreadsheet problem and the solution could have applicability to some of my own work. I'll take a stab at it if you will post the actual data in a spreadsheet.

RE: Percent of units experiencing conditions

As I posted in your annoyingly similar post elsewhere on eng-tips, you can either do it with statistics and maths, or a monte carlo sim of the population. The latter is easier and more fun, if less elegant.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Percent of units experiencing conditions

I like Monte Carlo sims too. Especially when you can bet on the outcomes...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close