A director of real estate sales, after several years of experience, decided that the best measure of effectiveness of a salesperson is the number of sales made, rather than, say, the value of their sales.

Four of her salespeople over the past year had the following results:

Person	A	B	C	D
Sales	12	16	10	14

At a 5% level of significance, can we conclude that the numbers of sales for each salesperson differ?