Join TSR now and chat about whatever you’re intoSign up now

Excel: Finding x values from y values using a trendline Watch

    • Thread Starter
    Offline

    1
    ReputationRep:
    Hi, so I have a scatter graph with a line of best fit or "trendline" as its called in excel and what I'm trying to do is create lines from specific y values across to the "trendline" and then down to the x axis to find the x value corresponding to the y value... Is this even possible? If it is please could someone with more knowledge than I let me know how to do it as soon as possible! Thanks in advance!
    Offline

    0
    ReputationRep:
    Choose to display the equation of the trendline and then do it with maths.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by majikthise)
    Choose to display the equation of the trendline and then do it with maths.
    Unfortunately I'm not that great at maths to be honest... The equation for the trendline is apparrently "y = 0.0312x + 0.0164" but that really dosent mean anything to me...

    I've come to realise that a paper graph may have been easier... I'll keep trying to do it in excel for now but If I can't do it by tomorrow evening I'll have to just go for the old fashioned method lol
    Offline

    0
    ReputationRep:
    I think he was telling you how to find values from x or y values.

    AFAIK, there's no way Excel will draw them on for you. The best way is probably to play around with Autoshapes.
    Offline

    2
    ReputationRep:
    (Original post by MALIK HAMID)
    Unfortunately I'm not that great at maths to be honest... The equation for the trendline is apparrently "y = 0.0312x + 0.0164" but that really dosent mean anything to me...

    I've come to realise that a paper graph may have been easier... I'll keep trying to do it in excel for now but If I can't do it by tomorrow evening I'll have to just go for the old fashioned method lol
    what that equation is saying is that for any given x value, you can calculate the y value by multiplying it by 0.0312 and adding 0.0164.

    So if you want to know what y is when x is 10, just do 0.0312*10 + 0.0164

    If you want to work out the x value for a given y instead, you just need to rearrange the equation to make x the subject, so for this it would be x = (y-0.0164)/0.0312


    I don't know what your graph looks like, but from the equation you've given, it sounds like the line of best fit should probably go through the origin. There is an option in the format trendline window called 'set intercept' which you can change it so that it does.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by alex-hs)
    what that equation is saying is that for any given x value, you can calculate the y value by multiplying it by 0.0312 and adding 0.0164.

    So if you want to know what y is when x is 10, just do 0.0312*10 + 0.0164

    If you want to work out the x value for a given y instead, you just need to rearrange the equation to make x the subject, so for this it would be x = (y-0.0164)/0.0312


    I don't know what your graph looks like, but from the equation you've given, it sounds like the line of best fit should probably go through the origin. There is an option in the format trendline window called 'set intercept' which you can change it so that it does.
    Thanks a lot this was really helpful!
 
 
 
Write a reply… Reply
Submit reply
Updated: November 10, 2010
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Poll
Is GoT overrated?
Useful resources

Articles:

The Student Room tech wikiTech forum guidelines

Quick link:

Unanswered technology and computers threads

Sponsored features:

Web Legend

Win a Macbook Air!

Blog about setting up a website for a chance to win in our Web Legend competition.

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.