This is the hardware part of getting accuracy. In many companies, limited access means having the area physically secured—fenced and locked. Psychological restrictions (lines on the floor, signs, roped-off areas) have also been proven to be effective.
This need for limited access is not primarily to keep people out, although that’s the effect. The primary reason is to keep accountability in. In order to hold the warehouse and stockroom people accountable for inventory accuracy, the company must give them the necessary tools. One of these is the ability to control who goes in and out. That means limiting access exclusively to those who need to be there.Only then can the warehouse and stockroom people be in control and legitimately be held accountable for results.
Let us add a word of caution about implementing limited access. It can be an emotional issue. In the world of the informal system, many people (group leaders, schedulers, buyers, etc.) spend a lot of time in the stockroom. This isn’t because they think the stockroom’s a great place to be. They’re in the stockroom trying to get components, to make the product, so they can ship it. It’s called expediting, and they do it in self-defense.