How to workout the exponential curve using x and y values and without excel

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SUMMARY

To derive an exponential curve from given x and y values without using Excel, users can explore alternative methods, although the data provided by Imran indicates a poor fit for an exponential model. The y-values are nearly constant, with one potential outlier, leading to a low r² value of approximately 0.5 for both exponential and linear fits. It is advisable to consult with an instructor regarding the suitability of the data for exponential modeling before proceeding with complex calculations.

PREREQUISITES
  • Understanding of exponential functions and curve fitting
  • Familiarity with statistical concepts such as r² values
  • Basic knowledge of data analysis techniques
  • Experience with alternative tools for data analysis (e.g., Python, R)
NEXT STEPS
  • Learn how to perform curve fitting using Python libraries such as NumPy and SciPy
  • Explore statistical analysis techniques to assess data quality and fit
  • Investigate the use of R for statistical modeling and curve fitting
  • Review methods for identifying and handling outliers in datasets
USEFUL FOR

Data analysts, statisticians, and students seeking to understand curve fitting and data modeling techniques without relying on Excel.

masterims
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Hi All,

I have searched for hours but cannot figure this out. I need to find the equation for an exponential curve but I only have the x and y values. Is there a way to do this without using excel?

I tried to follow this on YouTube: https://www.youtube.com/watch?v=ta4MZS7w2VA but the equation I got for the data below was different to what excel produces.

x......y
78.46......99.572
90.12......99.56
107.61......99.545
101.78......99.531
119.27......99.514
101.78......99.5
113.44......99.484
107.61......9.469

Thank you,
Imran
 
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masterims said:
Hi All,

I have searched for hours but cannot figure this out. I need to find the equation for an exponential curve but I only have the x and y values. Is there a way to do this without using excel?

I tried to follow this on YouTube: https://www.youtube.com/watch?v=ta4MZS7w2VA but the equation I got for the data below was different to what excel produces.

x......y
78.46......99.572
90.12......99.56
107.61......99.545
101.78......99.531
119.27......99.514
101.78......99.5
113.44......99.484
107.61......9.469

Thank you,
Imran

Hi masterims! Welcome to MHB! :)

Yes, there are other ways than to use Excel.
Actually, you can use Excel in other ways to find an exponential equation.

But before we go there, let's start with your data points.
From visual inspection, I can see that your x-data is distributed with a reasonable range.
However, your y-data is nearly constant (with 1 exception).
So it doesn't seem to match an exponential curve at all.

Moreover, you have a far outlier in your last data point.
Whatever you do, this will have a disastrous effect on any exponential curve match.
 
masterims said:
Hi All,

I have searched for hours but cannot figure this out. I need to find the equation for an exponential curve but I only have the x and y values. Is there a way to do this without using excel?

I tried to follow this on YouTube: https://www.youtube.com/watch?v=ta4MZS7w2VA but the equation I got for the data below was different to what excel produces.

x......y
78.46......99.572
90.12......99.56
107.61......99.545
101.78......99.531
119.27......99.514
101.78......99.5
113.44......99.484
107.61......9.469

Thank you,
Imran
I'm going to assume that the y value for the x = 107.61 data point is a typo (y = 99.459?), not an outlier. However the exponential fit and the linear fit to the data are both horrible: I get r^2 = 0.5 (or so) for both fits. So it doesn't matter what method you use...I can't think of a way to do it without Excel, unless you wish to do some time consuming calculator work. But seeing as you are going to get lousy results, I'd say talk to your instructor first.

-Dan