Menu Costs 

Why do firms not change their prices very  frequently? Obviously, the costs of changing prices at  frequent intervals and in small amounts must be more  than the benefits obtained from such a change. Firms prefer to wait before they make price changes in relatively large amounts and in the mean time absorb the losses that they would  suffer by not changing prices. This of course presumes that the firms  have  some monopolistic price setting power and  the  losses referred to above include lower profits  than would have been possible  if prices had been raised, and not necessarily actual out-of-pocket losses.

It  is  easy to understand  this  behaviour  of monopolistically competitive firms through the example of restaurants competing with each other. The term  'menu costs' immediately becomes meaningful as the costs that would be  incurred  in changing the menu cards every time there  is a change in the prices of items on the menu. These printing costs are surely negligible, but  the more  important costs are in terms of the loss of customers that a firm would face if it subjects its clientele to the 'irritability'  of continuous, small changes in prices. The concept  of menu costs in  a modem economy  is  indeed broad.  It  is  also widely applicable, given  the proliferation of automatic dispensers (e.g., coffee machines) and pay  telephones that operate on coins.  

It  is easy to  imagine  the cost that would be  incurred by  the suppliers if these ubiquitous machines were to be adjusted every time a price change is effected. The firms would rather not change their prices.  It  is  this idea  of weighing  the  costs  of  changing prices against the benefits obtained  from  changing prices that  is  formalised  in  the Mankiw model that we consider below.