There are more than a few things to consider, esp. ISO, exposure.
That said, the ability of the raw converter used plays a big part too. In my experience, Adobe's Camera Raw is not always the best converter to use. And neither is any ONE converter for ALL types of pictures.
from my understanding , RAW suppose to give u better control as in noise as compare to the compress JPEG format . I am a RAW believer but then sometime i need to shoot in JPEG if i dont have the time to process my photographs
in RAW, noise comes from the way you shoot the photo.
the usualy culprits are ISO, long exposure.
noise also becomes very visible when you try to brighten up extensively a very underexposed photo. example, increasing exposure on raw converters by +2 or more.
to prevent noise, shoot at the lowest iso possible, and shortest exposure possible.
RAW just gives you more post processing control and more details
If you are not using the manufacturer's own RAW convertor, you will most certainly have to adjust the noise reduction settings, sharpening, curves, exposure to get an optimal result. Such settings vary between different RAW convertors and you will have to get familiar with the software before you can obtain a satisfactory result.
A camera jpeg basically has undergone all of the above transformations.
There has been a kind of obsession with "clean images" with noise being evil with the coming of the digital age. Take a closer look at the noise pattern differences between raw and jpeg. You will probably find more detail in the noise of raw as compared to jpeg. If you don't like it, just run a noise reduction plugin and smother the details to look like the jpeg (same principle as "shoot in colour, convert into black and white later). For Canon, I'm not sure if the noise reduction can be turned off.
I normally select the highest RAW quality+fine. I prefer taking pics in RAW (3-4 MB) with JPEG (small size, 100kB).
Yes, I agree that RAW format need add. step to convert but anyway, all pics need to view right and appreciate after the hard work. What I have noticed is that the pics in RAW format will look slightly darker before converted and when compare with the converted one though. I normally keep the RAW and Converted-RAW for comparison. Of course if time permit though.