.
The THICKER the yarn, the FEWER stitches per inch.
The LARGER (THICKER) the needle, the BIGGER the stitches.
The BIGGER the stitches, the FEWER stitches per inch.
The THINNER the yarn, the MORE stitches per inch.
The SMALLER(THINNER) the needle, the SMALLER the stitches.
The SMALLER the stitches, the MORE stitches per inch
http://www.earthguild.com/products/knitcroc/marypat/gauge.htm