I am currently into my postgraduate degree in Applied Biostatistics and I am trying to figure out an answer to the following issue:

I have been given the below dataset:

**Age ----- Mortality Rate**

0 ------------ 5%

10 ------------ 8%

20 ------------ 9%

30 ------------ 7%

40 ------------ 11%

50 ----------- 14%

60 ----------- 22%

70 ----------- 28%

I have been asked to perform a cubic spline interpolation in order to find the missing values (mortality rates) for ages 1-9, 11-19, and so on.., until age 69.

I have performed the cubic spline interpolation using R and got the interpolated values for each age.

**My question**: Is there a way (some kind of a test?) to validate my model? To be more specific, is there some kind of test showing that the results produced are a good fit to the initial rates?

To be honest, I don't even know if my question is correct. Please feel free to ask for any clarification.

Thank you

John