In the previous article in this series we looked at the advantages offered by top down planning. In addition to the flexibility provided by top-down planning, many systems offer locking and floating facilities.
The concept of locking a number is simple enough. You may decide that the plan for Product X is one that you do not wish to change regardless of other changes that you may make. You therefore place a lock on this number.
| Sales | Locked | |
|---|---|---|
| Product Group 1 | 6,000 | |
| Product X | 1,000 | Lock |
| Product Y: | 2,000 | |
| Product Z | 3,000 |
What happens now when you make a top-down change to the parent of that product?
| Original Sales | Locked | New Sales | |
|---|---|---|---|
| Product Group 1 | 6000 | 7,000 | |
| Product X | 1000 | Lock | 1,000 |
| Product Y: | 2,000 | ? | |
| Product Z | 3,000 | ? |
The non-locked items will have to soak up the change. These numbers are said to “float”
| Original Sales | Locked | New Sales | |
|---|---|---|---|
| Product Group 1 | 6,000 | 7,000 | |
| Product X | 1000 | Lock | 1,000 |
| Product Y: | 2,000 | 2,400 | |
| Product Z | 3,000 | 3,600 |
In this case Product Y and Product Z’s new sales values are calculated by subtracting the total of locked elements from the total (7,000 – 1,000). The remaining number (6,000) is then pro-rated across the remaining non-locked elements (6,000 x 2,000/5,000) & (6,000 x 3,000 / 5,000) respectively.
In this way users are offered great flexibility in planning top down.
There are, as you might expect, a few caveats that we should bring to your attention here.
Firstly we need to ask what happens when you lock all the elements and then make a change to the parent. The change must, of course, logically be rejected and the total will revert to the existing total.
Secondly we have to ask whether locks are transient or durable. In other words when you have finished a planning session do you expect any locks you have created to persist to the next session, or will they be cleared on exit.
The obvious answer here is that you would expect them to persist. Be aware however that not all systems provide this functionality. Indeed there is a very good case to be made for clearing them. Merchandise planning is at least a 3 dimensional process. In order to allow it to be accomplished on the 2 dimensional medium of a computer monitor there is always going to be data that is not displayed. Users find it very difficult to maintain a grip on where locks have been placed when they are not immediately visible. This leads to complications when “invisible” locks lead to unexpected results when planning top-down.
Consider the example of a user planning sales by product by store, and viewing a range of products by a single store on each “page” of the screen.
| Store 1 | Sales | Locked |
|---|---|---|
| All Products | 150,000 | Locked |
| Product A | 1,000 | |
| Product B | 2,000 | |
| …. | ||
| Product Z | 7,000 |
Whilst she may lock several store totals in individual “pages” and be able to see they are locked, usually by the use of colour coding, she will not be able to see these colour coded locks on one screen unless she changes the view to one that shows all of the store totals at once.
| All Products | Sales | Locked |
|---|---|---|
| Store 1 | 150,000 | Locked |
| Store 2 | 175,000 | |
| Store 3 | 120,000 | Locked |
| Store 4 | 200,000 | |
| …. | ||
| Store 1000 | 75,000 |
When she makes a change to the All Store Total the pro-ration may not therefore be as she expects it to be. This is a relatively simple example. In practice things get a lot more complicated. Having locks persist across sessions simply magnifies the problem. In conclusion, then, we can see that the use of locking and floating adds considerable flexibility to the standard top-down planning facilities offered by most major vendors.
This flexibility, though, needs to be used with care.
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