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safety stock

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