Charting question

[wenlianglo]

How do I extrapolate a graph which do not have a formula for the graph?
At the end of the graph, I found that I don't have enough data and would want to have a longer graph?

 

[Andrew Poulsom]

Have you tried adding a trend line?

 

[wenlianglo]

I used "scatter with smooth line".
If I add trend line "polynomial", that ignore some of my data which makes it inaccurate.

 

[Andrew Poulsom]

Maybe you could use the FORECAST function to calculate the remaining values and plot them.

 

[wenlianglo]

FORECAST is based on linear function, so my scattered graph if forecasted will have straight lines at that part.
Any other suggestion?

 

[Andrew Poulsom]

What method would you like to use to forecast the missing values?