Stripes, odd patterns, large areas of color?

Can someone help a newbie to what yarn to buy to create different color effects?
I tried a yarn that said it was suppose to stripe and it turned out a mess. Is there a calculation on stitches per inch and how long the color is on the yarn before it changes?

It will depend on a number of things like how long the color repeat is, what stitch you are using, what you are knitting and how large of an item you are knitting. (a sock will have a different stripe than a sweater using the same yarn)

There was a great segment on Knitting Daily a few years ago about this very thing.

That is the exact information I am looking for.

You’ll have to search but there is a segment about it on http://www.knittingdaily.com/