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OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???

Posted By: leobueno
Date: Sunday, 29 January 2012, at 7:20 p.m.

In Response To: OT: Converting y = Ae^bx to base 10 (Jason Lee)

I am wondering what coefficient Excel uses.

If I do a series which I grow at 10%, say

YEAR,AMOUNT

0,100

1,110

2,121

3,133

. . .

Excel displays the regression equation as

y = 100.0e^0.095310x (with R^2 = 1.0, so it's got the perfect fit)

but if we calculate c from c = b log10(e), we get

c = 0.09531 * 0.4342945 = 0.0414

Yet we know c was 0.10, since that's the rate at which we grew the series.

So either I am doing something wrong or Excel reports a weird value for b.

Messages In This Thread

• OT: Converting y = Ae^bx to base 10
  leobueno -- Sunday, 29 January 2012, at 3:12 p.m.
  • OT: Converting y = Ae^bx to base 10
    Casper van der Tak -- Sunday, 29 January 2012, at 3:22 p.m.
    • OT: Converting y = Ae^bx to base 10
      Jason Lee -- Sunday, 29 January 2012, at 3:48 p.m.
      • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
        leobueno -- Sunday, 29 January 2012, at 7:20 p.m.
        • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
          Sam Pottle -- Sunday, 29 January 2012, at 9:14 p.m.
          • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
            Jake Jacobs -- Monday, 30 January 2012, at 2:38 a.m.
            • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
              Michael Petch -- Monday, 30 January 2012, at 3:56 a.m.
          • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
            leobueno -- Monday, 30 January 2012, at 1:44 p.m.
            • OT: Converting y = Ae^bx to base 10 - How does Excel calculate b ???
              Sam Pottle -- Monday, 30 January 2012, at 3:43 p.m.