One standard to rule them all
Yes, the idea that one standard can be established for everyone. By forcing compliance we will have peace on earth, and yes, our clothes will fit! Considering the variety of shapes and sizes in the United States alone, the idea is really a fantasy.
- One standard guarantees that some of the population will not have any clothes that fit. One could argue this situation exists today, so why not try one standard. With no allowance to adapt to fit the wide range of shapes and sizes, then outliers will never have clothes that fit.
- Our population is constantly changing. The most recent sizing study revealed that we are taller and weigh more than we did in the past. One standard would quickly become outdated.
- Sizing studies are very expensive and labor intensive. Studies are not done frequently, so manufacturers will always be behind what is happening in the real world.
Loosely conforming to a standard while yet adapting to meet a customer's need.
Even if one standard to rule them all is unrealistic, we still need a standard. ASTM and the latest Sizing USA study have provided us with a standard that any manufacturer can use (for a price, of course). These measurement and sizing specs can act as a guide, a place to start. As a manufacturer develops their customer profile, they can adapt these standards to meet the needs of their customer.
Over the years, it's important to compare your product against these standards. I've seen patterns and sizing drift from these standards naturally through errors. These errors are not intentional, they just happen and can easily pass from one style to the next. So a careful study and comparison can bring things back. This includes measuring fit models and comparing them against the standard and analyzing customer returns due to fit issues.
In-house size standardization
Once a sizing standard is established for a brand, it is important to adhere to that standard during product development. As an example, all new pants styles have the same finished length and waist sizes as specified. Variations in fit can come from multiple sources due to fabric variations (or problems), construction issues (taking too big/small a seam allowance, cutting errors), or variations in a pattern. You have to be careful not to draft a pattern from scratch every time. Pattern makers in the industry will use the patterns from an already proven style to develop the new style. This practice ensures consistent fit across styles. A quality control process through each step of development and production is necessary to find problems before they become big ones.
A few words on vanity sizing
Vanity sizing implies that a manufacturer wilfully chooses to ignore a size standard and relabel a size smaller than it actually is. I do not believe there is a vast conspiracy to do this intentionally. Instead I think manufacturers are trying to meet the needs of their customers while trying to conform to a standard.
*This blog entry was inspired from my reading in the book Sizing in Clothing and more specifically the article Sizing Standardization by K. L. LaBat. I made very few notes on this article and don't remember much of what I read. I did make a note that LaBat tried to prove the existence of vanity sizing by studying children's age-based sizing. I thought the argument was rather weak.