You don't use a cubic spline to average data at a given point. You really want to do that BEFORE you use a cubic spline.
Next, a cubic spline is typically an INTERPOLATING spline, so it won't smooth your data. It will pass directly through the data points.
Finally, you did NOT attach any data. You attached a small PICTURE of your data, which is completely useless unless someone were to try to type in your complete data set. I hope they have very good eyesight if they do. Is there a good reason why you want to make it more difficult for someone to help you?
If you really want help, then it would be best if you actually attach the true data. Do so either by pasting in the data as text, or by attaching a .mat file. A spreadsheet is also acceptable, but it takes slightly more effort for someone to read it in, IF they were going to try to help you. Again, is there a good reason why you want to make it difficult to get timely help? Please edit your question, or attach your data to a comment on your question. (Do not answer your question with the data, as many seem to do.)
