I have some sample data, I draw a trending line which gives me equation as well. But I found that the trending line sometimes isn't trustworthy at all.

The trending line graph doesn't match the equation!

I think that's unacceptable and totally out of my expectation. Why is it?

Sample data:

count(x)    runtime(y)
1000         0.1
2000         0.8
4000         6.4
8000         51.1

How to reproduce it: Draw a scatter plot, add a trending line, choose Exponential. Then try to calculate by the given equation, when x = 4000, 7000, 8000. And you can see y doesn't match the graph at all.

fileLink: https://anonfile.com/A4m0F7lbb3/sheet1_-_copy_xlsx


enter image description here

  • @cybernetic.nomad Got same result, my friend. They're the same equation I think. – Rick Nov 21 '18 at 16:16
  • You are correct. I can't explain it either – cybernetic.nomad Nov 21 '18 at 16:31

Found it:

The problem is the equation has some rounding in it. If you right-click on it and select Format trendline label:

enter image description here

You can add decimal places:

enter image description here

and get a more precise result:

enter image description here

  • You are a genius! – Rick Nov 22 '18 at 1:22

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