How to interpolate data

Question

Level 1

140 points

How to interpolate data

Hi
This can be done in excel where there is missing data and excel interpolates and joins the line with the next available data point on a line chart. Please help I can't find the option in Numbers.

Powerbook G4, Mac Mini (intel Duo), Mac OS X (10.4.7)

Posted on Aug 23, 2007 6:06 AM

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Answer 1

WWJD

Level 6

15,830 points

Aug 23, 2007 4:31 PM in response to iahmed

In the "old days" when 123 and Excel could not do this we would create an equation to calculate the missing value. It appears that numbers does not support missing values (that I know of).

Regards,

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Answer 2

Aug 25, 2007 7:00 PM in response to iahmed

I agree that you will need to interpolate manually in the table and plot the resulting full data set in the graph.

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Answer 3

WWJD

Level 6

15,830 points

Aug 25, 2007 7:21 PM in response to iahmed

Here's a quick visual example:

Regards,

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Answer 4

iahmed Author

Level 1

140 points

Aug 27, 2007 8:02 AM in response to WWJD

Hi WWJD,

Thanks for your reply. My table has more than one missing data point for e.g days 1,3,5,7 and I have data for day 1 and 7. How do you suggest I make up the data in between and I don't want numbers to plot the data point but just connect the line from 1 to 7. Please let me know if this can be done.

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Answer 5

KOENIG Yvan

Level 8

41,819 points

Aug 27, 2007 11:37 AM in response to iahmed

Hello

Assuming that you have a value in D1 and an other one in D7.
In D2, enter
==D1+(D$7-D$1)/6
fill dow from D2 thru D6
You will have your interpolated values.
Of course, you may wish to complete with some rounding.

CAUTION, due to a localisation bug, the absolute references are usable ONLY if your system is using $ as currency symbol.

Yvan KOENIG (from FRANCE lundi 27 août 2007 20:37:19)

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Answer 6

WWJD

Level 6

15,830 points

Aug 27, 2007 2:29 PM in response to iahmed

I'm afraid with the current version of Numbers, the interpolated values will also be plotted versus the connecting lines only. Not quite what you want. Please make sure you leave Feedback to Apple regarding Scatter Plots and interpolated data.

Regards,

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