How to improve product availability?
First, it is recommended to determine the right target service levels for each item. How much does each product contribute to sales, how many different customers order the product, and so how important is it to have this item available online? Obviously, important items should have higher service levels, leading to higher safety stocks.
Should the item stock out, think of what would be the best strategy to deal with this. Would it make sense to not show the item online anymore until the new stock comes in, so the customer cannot order the item that is currently not available? Maybe, but this can only be done for non-branded items from the long tail. If your A-item is not even visible online, there is a chance of losing market share. And if an item is temporarily not available, it makes sense for consumers to know when they can expect the product to be back in stock. So, another option is to show the estimated time of arrival, this will pay off since consumers will know when they can expect the product.