[pshrynk]

Portion sizes in pre-packaged goods vary according to the cost of materials. Usually quite small in their swings. A food processor wants to maintain the same price point to attract repeat customers. A bag of chips that costs $.50 to manufacture and ship and costs $1.00 at teh store will range from 1 to as much as 3 ounces, depending on the cost of materials and shipping. We only really notice in times like these where there is a sharp upswing in prices, leading to downsized packaging. As things stabilize, the package sizes will increase, using such strategems as "x% extra" or "jumbo size" to signal you that you're getting a bargain.