Solved

# Determine slope intercept y=mx+b from 2 arrays

Posted on 2013-01-16
476 Views
Hi All -

Ironically, I'm quite handy with data, but pretty bad at Math.  I'm in the process of building a revenue forecasting tool and have a good way to forecast calls.  What I want to do now is apply a slope intercept formula to forecasted calls to guess how many orders those calls will yield.

See the attached spreadsheet for an example of what I'm talking about.  You can ignore the formulas as i just used them to generate some example data.  What I really want to understand is how Excel comes up with the y=mx+b formula that it shows on the graph.

Please explain the math to me as if I were in 6th grade (like i said... not my strong point).

Also - please don't offer any suggestions on spreadsheet formulas I could use to apply the slope intercept as the tool isn't Excel based.  I just need to understand the "paper and pencil math" so i can re-produce it in-memory
Slope-for-EE.xlsx
0
Question by:ducky801
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• 2

LVL 84

Expert Comment

ID: 38785356
0

LVL 12

Accepted Solution

PCableGuy earned 500 total points
ID: 38785378
0

LVL 84

Expert Comment

ID: 38785406
Minimizing the sum of the squares of the differences between mx+b and y
gives the maximum likelyhood estimator under the assumption that the y values were produced from mx+b  +  independent Gaussian errors.

Taking the derivatives of the sum of the squares of the differences with respect to m and b
and setting them to 0 finds the minimum.
Each constraint is a linear equation on m and b, and solving them simultaneously gives
the standard formula.
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

### Suggested Solutions

Excel Auto-Complete lines 4 34
Open attachments in viewer, not main app 4 32
Cell Manipulation 37 56
How do I buy BitCoin? 4 31
A little background as to how I came to I design this code: Around 5 years ago I designed an add-in that formatted Excel files to a corporate standard, applying different cell colours and font type depending on whether the cells contained inputs,…
This article seeks to propel the full implementation of geothermal power plants in Mexico as a renewable energy source.
This Micro Tutorial demonstrates how to create Excel charts: column, area, line, bar, and scatter charts. Formatting tips are provided as well.
Many functions in Excel can make decisions. The most simple of these is the IF function: it returns a value depending on whether a condition you describe is true or false. Once you get the hang of using the IF function, you will find it easier to us…
###### Suggested Courses
Course of the Month1 day, 21 hours left to enroll