Thanks for the Advice on the scatter chart. now that i have these i'm still abit confused.
So assuming total need exp is series 1 exp between levels is series 2 and then the second difference is series 3
the formulas i got from the scatter graph are wierd and they change abit wierd aswell. let me try and explain.
The series 1 formula is as follows
y= 4x2 + 10x + 6E-11
The series 2 formula is y= 4E-16x2 + 8x + 6
The series 3 formula is y= 1E-17x2 - 2E-15x + 8
Now thats if i have the scatter graph for all the data from #1 - 100
I know that the series 2 formula is ment to be y = 8x + 6 (tested and its perfect)
Series 3 is ment to just be Y = 8 (because we know that the 8 is constant)
Im wondering if the wierd formulas is because Number 1 on my table has 2 empty cells?
Any further advice? 
Hi DragonPrinces, I think you're on the right track.
Just a note, those words are spelled "weird", and "meant".
Anyway, you are right that the first column (ignoring the level numbers) is the experience needed at each level, the second column is the first difference of the experience between levels, and the third column is the second difference, i.e. the difference of the differences.
You only need to fit a quadratic trendline to the first column (series 1) because that's the trend you're trying to figure out: how does the experience needed vary with level? You don't need to compute trendlines for the second and third columns, because those aren't the trends you're trying to figure out.
You should think critically about the numbers you're getting:
4x
2 + 10x + 6e-11
Well, the constant term is 6e-11, which is a computer's way of writing 6 x 10
-11. That is 0.00000000006, which is so small, it's effectively zero. It's just a numerical artifact due to the slight imprecision of the numbers as they are represented in computer memory. The program tried to fit a full second-order polynomial with quadratic, linear, and constant terms, but the data have no constant term, so the fitter found a really small value for it (small enough to be ignored completely). The answer you got is effectively just 4x
2 + 10x
The same thing happened to the second column. You tried to fit a quadratic to data that is just linear (a straight line). As a result, the fitter found an extremely small coefficient for the second-order (x
2) term. 4e-16 = 0.0000000000000004, which is effectively 0. It's saying there is no second-order term, and the answer is effectively just 8x+6
The same thing happened with the third column. You tried to fit a quadratic curve to data that are constant (straight, flat line). So the coefficients on the second-order (x
2) and first-order (linear, x) term came out to be incredibly tiny. It's saying that these terms basically don't exist, and the answer is just y = 8.
The question is, do these answers work?
The answer for the second column works
y = 8x + 6
for x = 1, y = 8(1) + 6 = 14 (you have this space listed as blank, but this answer implicitly assumes there is a level 0 needing experience 0, so that the difference between levels 1 and 0 is 14).
for x = 2, y = 8(2) + 6 = 16 + 6 = 22
for x = 3, y = 8(3) + 6 = 24 + 6 = 30
for x = 4, y = 8(4) + 6 = 32 + 6 = 38
for x = 5, y = 8(5) + 6 = 40 + 6 = 46
for x = 44, y = 8(44) + 6 = 8(40 + 4) + 6 = 8(40) + 8(4) + 6 = 320 + 32 + 6 = 352+6 = 358 (why use a calculator when you don't need to?
)
Does the answer for the first column work?
y = 4x
2 + 10x
for x = 1, y = 4(1)
2 + 10(1) = 4 + 10 = 14
for x = 2, y = 4(2)
2 + 10(2) = 4(4) + 20 = 16 + 20 = 36
for x = 3, y = 4(3)
2 + 10(3) = 4(9) + 30 = 36 + 30 = 66
for x = 4, y = 4(4)
2 + 10(4) = 4(16) + 40 = 64 + 40 = 104
for x = 5, y = 4(5)
2 + 10(5) = 4(25) + 50 = 100 + 50 = 150
for x = 44, y = 4(44)
2 + 10(44) = 4(1936) + 440 = 7744 + 440 = 8184 (I cheated and used a calculator for this one)
So we have our answer. If y is the experience needed at level x, then the relationship between y and x is given by the equation:
y = 4x2 + 10x
