a buffer of extra inventory used as protection against a stockout (i.e., running out of inventory)
sample mean
the mean of a subset of the population data
satisfactory solution
in a goal programming model, a solution that satisfies the goals in the best way possible
sample
a portion of the items produced used for inspection
scatter diagram
a diagram used in forecasting that shows historical data points
scientific method
a method for solving problems that includes the following steps: (1) observation, (2) problem definition, (3) model construction, (4) model solution, and (5) implementation
search techniques
methods for searching through the solutions generated by a simulation model to find the best one
seasonal factor
a numeric value that is multiplied by a normal forecast to get a seasonally adjusted forecast
seasonal pattern
in a forecast, a movement that occurs periodically and is repetitive
seed value
a number selected arbitrarily from a range of numbers to begin a stream of random numbers generated by a computerized random number generator
sensitivity analysis
the analysis of changes in the parameters of a linear programming problem
sequential decision tree
a decision tree that analyzes a series of sequential decisions
service level
the percentage of orders a business is able to fill from inventory in stock during the reorder period
service rate
the average number of customers that can be served from a queue in a specified period of time
shadow price
the price one would be willing to pay to obtain one more unit of a resource in a linear programming problem
shared slack
in a CPM/PERT network, slack that is shared among several adjacent activities
shortest route problem
a network problem in which the objective is to determine the shortest distance between an originating point and several destination points
short-range forecast
a forecast of the immediate future that is concerned with daily operations
simple regression
a form of regression that reflects the relationship of two variables
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simplex method
a tabular approach to solving linear programming problems
simplex tableau
the table in which the steps of the simplex method are conducted ; each tableau represents a solution
simulated time
the representation of real time in a simulation model
simulation
the replication of a real system with a mathematical model that can be analyzed with a computer
simulation language
a computer programming language developed specifically for performing simulation
single-server waiting line
a waiting line that contains only one service facility at which customers can be served
slack variable
a variable representing unused resources that is added to a inequality constraint to make the constraint an equation
slope
the rate of change in a linear mathematical function
smoothing constant
a weighting factor used in the exponential smoothing forecasting technique
standard deviation
a measure of dispersion around the mean of a probability distribution
states of nature
in a decision situation, the possible events that may occur in the future
steady state
a constant value achieved by a system after an extended period of time
steady-state probability
a constant probability that a system will end up in a particular state after a large number of transition periods
stockout
running out of inventory
subjective probability
a probability that is based on personal experience, knowledge of a situation, or intuition rather than on a priori or a posteriori evidence
substitution method
a method for solving nonlinear programming problems that contain only one equality constraint; the constraint is solved for one variable in terms of another and is substituted into the objective function
surplus variable
a variable that reflects the excess above a minimum resource requirement level; it is subtracted from a inequality constraint in a linear programming problem
system
a set or an arrangement of related items that forms an organic whole
inequality constraint to make the constraint an equation 
inequality constraint in a linear programming problem 