Editing Supply and demand (section)

===Supply schedule===
A supply schedule, depicted graphically as a supply curve, is a table that shows the relationship between the price of a good and the quantity supplied by producers. Under the assumption of [[perfect competition]], supply is determined by [[marginal cost]]: Firms will produce additional output as long as the cost of extra production is less than the market price.

A rise in the cost of raw materials would decrease supply, shifting the supply curve to the left because at each possible price a smaller quantity would be supplied. This shift may also be thought of as an upwards shift in the supply curve, because the price must rise for producers to supply a given quantity.  A fall in production costs would increase supply, shifting the supply curve to the right and down. 

Mathematically, a supply curve is represented by a supply function, giving the quantity supplied as a function of its price and as many other variables as desired to better explain quantity supplied. The two most common specifications are:

1) linear supply function, e.g., the slanted line 
:<math> Q(P) =   3P  - 6 </math>, and

2) the constant-[[Elasticity (economics)|elasticity]]<ref>The [[elasticity coefficient]], or often just ''elasticity'', is an important parameter in [[metabolic control analysis]], used to express the local response of an enzyme or other chemical reaction to changes in its environment.</ref> supply function (also called [[isoelastic function|isoelastic]] or log-log or loglinear supply function), e.g., the smooth curve
:<math> Q(P) =  5P^{0.5}  </math>
which can be rewritten as 
:<math> \log Q(P) =  \log 5 + 0.5 \log P   </math>

The concept of a supply curve assumes that firms are perfect competitors, having no influence over the market price. This is because each point on the supply curve answers the question, "If this firm is faced with this potential price, how much output will it sell?" If a firm has market power—in violation of the perfect competitor model—its decision on how much output to bring to market influences the market price. Thus the firm is not "faced with" any given price, and a more complicated model, e.g., a [[monopoly]] or [[oligopoly]] or [[product differentiation|differentiated-product]] model, should be used.

Economists distinguish between the supply curve of an individual firm and the market supply curve. The market supply curve shows the total quantity supplied by all firms, so it is the sum of the quantities supplied by all suppliers at each potential price (that is, the individual firms' supply curves are added horizontally).

Economists distinguish between short-run and long-run supply curve. ''Short run'' refers to a time period during which one or more inputs are fixed (typically [[physical capital]]), and the number of firms in the industry is also fixed (if it is a market supply curve). ''Long run'' refers to a time period during which new firms enter or existing firms exit  and all inputs can be adjusted fully to any price change. Long-run supply curves are flatter than short-run counterparts (with quantity more sensitive to price, more elastic supply).

Common determinants of supply are:

# Prices of inputs, including wages   
# The technology used, [[productivity]]  
# Firms' expectations about future prices
# Number of suppliers (for a market supply curve)