This is a Quora question and here is my answer.

Buyers are very busy and have tough jobs. Obvious ways in which suppliers can be helpful are strong product sales, marketing and tradespend support, and limiting out-of-stocks.

Category management by the supplier also helps the buyer and can position the supplier as a strong category player. The following encompass strong supplier category management practices and how they can help the buyer:

  • Review the category performance for the retailer and the market as a whole, including specific brand and item performance, not just for your products, but those of competitors and others in the category;
  • Do pricing, promotion and location analysis of all products in the category; identify ways in which your products and others can be improved in these areas.
  • Conduct deeper analysis to highlight category and market trends, especially relative to the retailer.
  • Educate the category buyer about category and market trends relative to your brand and products and other brands and products.
  • Make recommendations to help the buyer grow their category and bring in new customers. Include not just how your products fit, but also others. Be balanced in your approach and discussion between your products and others.
  • Understand the buyer’s demographic profile relative to those shopping the category; is that difference working against you or the buyer from increasing your product and overall category sales? If so, you may need to point this out to the buyer.

Many of these require category data that is only accessible through the retail data providers: Spinsscan for natural/organic, Nielsen and IRI for conventional channels excluding Wal Mart.
Good brokers can be a great source of information, mostly anecdotal, but still valuable nonetheless.

In reality, I think only the mid-to-large CPG firms will absolutely do all of this and do it well because it takes manpower, which most smaller CPG firms cannot afford.