If the only element of the three that changed was the closing ratio, then the sales increase was the result of the additional staff. One chain discovered that their television advertising in one market didn't increase traffic. Their sales increases came from a better closing ratio and higher average sale generated by the same amount of traffic. They found that they got the same sales results with in-store signage at much less cost than their television advertising. The retail equation can even help you determine whether or not you need to advertise.
Many retail executives believe they sell most of the traffic that comes to their stores.
If you sell to most of your traffic, and the rest is children, or husbands accompanying wives or visa vice-versa, then you'll need to increase your traffic if you want to increase sales. If your stores are service-sensitive, chances are that a few more staff hours during busy periods like lunch hours, evenings, Saturdays, and Sundays would produce better sales increases for less cost than your advertising. And with the retail equation, you'll be able to precisely measure the impact of each. At the store level, the manager returns after a day off to find that sales during the day off were not what the budget called for. Unfortunately, they didn't spend enough time selling.