# Thread: Logarithmic Trendline (Windows 2000 Pro)

1. ## Logarithmic Trendline (Windows 2000 Pro)

I have a table consisting of the following info: (1) 1st column listing years 2000-2003; (2) 2nd column listing home sales for each of those years. I created a line chart with the Years on the X-axis and # home sales on the Y-axis. I then created a trendline using the logarithmic "type" going out 4 years to Year 2007. However, I want the forecasted values for Years 2004-2007 to appear in the table. I have tried all sorts of equations using LINEST and LOGEST and cannot replicate the values that are represented by the trendline in the chart. How can I do this? I look forward to your response. (By the way, I have not had a problem with creating a linear trendline and calculating the forecasted linear values, but everytime that I have attempted using LINEST or LOGEST, i get some nonsensical result.) I look forward to your help.

2. ## Re: Logarithmic Trendline (Windows 2000 Pro)

This is possible, but it would be helpful if you could post a small sample workbook.

3. ## Re: Logarithmic Trendline (Windows 2000 Pro)

Linest is for linear trends, logest is for exponential (not logrithmic).

Try:
<pre>=LINEST(YValues,LN(XValues))</pre>

Where XVAlues and YValues are your X and Y ranges.

Steve

4. ## Re: Logarithmic Trendline (Windows 2000 Pro)

Please see attached workbook for example of table and chart.

5. ## Re: Logarithmic Trendline (Windows 2000 Pro)

Here is the formula for cell E9:

=TREND(\$E\$5:\$E\$8,LN(ROW(1:4)),LN(ROW()-4))

See attached workbook. Your chart doesn't have x values defined, so I used the ROW function to provide the x values for the TREND function. You could also put the values 1 through 8 in B5:B12 and refer to these instead.

6. ## ThanksRe: Logarithmic Trendline (Windows 2000 Pro)

Thank you very much.

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