Grant Foster has written another post about data analysis in his Open Mind blog. This time he analyzes visual Cepheid data and compares it with published photometric data. His conclusion:
Yes, Virginia, visual data really can compete with professional photometry. But to do so requires large quantities of data. Experience and skill on the part of the observer doesn’t hurt either! It’s a lot of effort to accumulate nearly 5,000 visual observations of just one star (and Wayne Lowder observed a lot more than just this one star!), but its scientific value is tremendous. The value of the data set taken as a whole is comparable to that from professionals.
Amateur astronomy, whether by high-tech or just by eye, is a rewarding task, both for the observer and the analyst.
Here is a light curve he made of data from Wayne Lowder, a famous AAVSO visual observer, compared with published professional data:
Click here to read the blog which goes into much more detail,  but is quite accessible for new observers too. Grant's writing is really good at being entertaining and useful to many different skill levels.