
ptg6843605
house of quality − hypergeometric distribution
Page 163 The Encyclopedia of Operations Management
mapping concepts developed by Kaplan and Norton (1990), the Y-tree concept used at 3M, and the causal
mapping tools as presented by Hill (2011c). A strategy map requires the causal linkages: learning & growth
internal customer financial. In contrast, the X-Matrix requires the causal linkages: process tactics
strategies results. In this author’s view, an X-Matrix is more general than a strategy map, a Y-tree is more
general than an X-Matrix, and a causal map is more general than a Y-tree. However, some industry experts
argue that hoshin planning is unlike other strategic planning methods because it has more accountability and
more “catchball” interaction between levels in the organization.
See alignment, balanced scorecard, catchball, causal map, lean thinking, Management by Objectives
(MBO), mission statement, PDCA (Plan-Do-Check-Act), strategy map, Y-tree.
house of quality – See Quality Function Deployment (QFD).
hub-and-spoke system – A distribution system used by railroads, motor carriers, and airlines to consolidate
passengers or shipments to maximize equipment efficiency.
Many passenger airlines in North America, such as Delta and United, have hub-and-spoke networks, where
the hub is a central airport and the spokes are the routes that bring passengers to and from the hub. In contrast,
the direct route (or point-to-point) system does not use a central hub airport. In North America, Southwest
Airlines is an example of a direct route system. The hub-and-spoke system is an important distribution strategy.
For example, FedEx, a delivery service, has a hub in Memphis, with all FedEx shipments going through this hub.
See consolidation, logistics.
human resources – (1) The employees in an organization. (2) The organizational unit (department) charged with
the responsibility of managing employee-related processes such as hiring, orientation, training, payroll, benefits,
compliance with government regulations, performance management (performance management, performance
reviews), employee relations, employee communications, and resource planning; sometimes called the personnel
organization; often abbreviated HR.
See absorptive capacity, addition principle, back office, business process outsourcing, cost center, cross-
training, delegation, division of labor, empowerment, Enterprise Resources Planning (ERP), ergonomics,
gainsharing, Hawthorne Effect, High Performance Work Systems (HPWS), job design, job enlargement, job
rotation, labor grade, lean sigma, learning curve, learning organization, multiplication principle, on-the-job
training (OJT), operations management (OM), organizational design, outsourcing, pay for skill, productivity,
RACI Matrix, Results-Only Work Environment (ROWE), scientific management, self-directed work team, Service
Profit Chain, service quality, standardized work, subtraction principle, unfair labor practice, value chain, work
measurement, work simplification, workforce agility.
hypergeometric distribution – A discrete probability distribution widely used in quality control and auditing.
The hypergeometric distribution is useful for determining the probability of exactly x defective units found in
a random sample of n units drawn from a population of size N that actually contains m defective units. It is a
particularly useful distribution for acceptance sampling and auditing. The normal, Poisson, and binomial
distributions are often used as approximations for the hypergeometric distribution.
The hypergeometric distribution can be used to create confidence limits on the number of errors in a
population based on a sample. For example, an auditor can take a sample and then conclude with a 95%
confidence level that the true percentage of errors in the population is no more than p percent. The auditor can
also use this distribution to estimate the sample size required to achieve a desired confidence limit. Most
statistics textbooks recommend using the normal distribution for the proportion defective; however, this is an
approximation for the hypergeometric distribution and will be inaccurate when the error rate is small.
Parameters: Population size N and sample size n.
Probability mass function:
( ) ( , , , )
m N m N
P X x p x N n m
n x n
, where x is the number of
successes in the sample, n is the sample size, m is the number of successes in the population, and N is the size of
the population. The distribution function is simply the summation of the mass function.
Statistics: Range [a,b] where max(0, ( ))a n N m
and min( , )b m n
, mean πn, variance
(1 ) ( ) / ( 1)n N n N
, where π = m/N. The mode has no closed form.