Statistics Are Inaccurate
Your Analysis is Faulty (How to lie with drug statistics)
By John Horgan
Published: April 2, 1990
In the war on drugs, J. Michael Walsh is one of the administration's
most valuable officers. His mission is to implement -- and, more
important, to justify -- programs in which the urine of working people is searched for
signs of illegal drugs. Walsh designed the drug-testing program for federal employees
mandated by Ronald Reagan several years ago and is now advising business leaders on
how to test their workers. He has argued in favor of testing before Congress and federal
judges, on national radio and TV shows, and in countless other public forums.
Walsh's basic message is this: drug users, from crack addicts to weekend marijuana
smokers, make less productive workers than non-users. So employers are justified in
using drug tests -- which cannot distinguish between chronic abuse on the job and
occasional use at home -- to root out all users from the work force.
Other officials say the same thing, but Walsh's title gives his words extra weight. He is
director of the Division of Applied Research and the Office of Workplace Initiatives at
the National Institute on Drug Abuse (NIDA), the chief federal drug research agency.
The evidence he marshals is passed on to drug czar William Bennett and is widely
disseminated, with the federal government's seal of approval. This role, and Walsh's
status as a scientist, oblige him to uphold high standards of objectivity and competence.
More than any other person, he is responsible for the intellectual honesty of the whole
Reagan-Bush drive for workplace testing. A look at some of the central claims he has
made in support of that drive reveals that he has not met his responsibility.
Two years ago Walsh testified in federal court that the "cost of drug abuse to U.S.
industry" was nearly $50 billion a year, according to "conservative estimates." This claim
is a staple of anti-drug rhetoric. It is frequently quoted without qualification by the media,
and last year President Bush rounded it upward to "anywhere from $60 billion to $100
Here's how the figure was derived. In 1982 NIDA surveyed 3,700 households around the
country. The Research Triangle Institute (RTI), a NIDA contractor in North Carolina,
then analyzed the data and found that the household income of adults who had ever
smoked marijuana daily for a month (or at least twenty out of thirty days) was twentyeight percent less than the income of those who hadn't. The RTI analysts called this
difference "reduced productivity due to daily marijuana use." They calculated the total
"loss," when extrapolated to the general population, at $26 billion. Adding the estimated
costs of drug-related crimes, accidents, and medical care produced a grand total of $47
billion for "costs to society of drug abuse."
Several things are wrong here, but the most glaring is the simpleminded conclusion that
marijuana smoking caused the lower incomes with which it was associated. There are
many respects in which the behavior of lower-income people differs statistically from
that of upper-income people, but this mere correlation never establishes causality. It is
quite probable, for example, that people who would admit to watching "Wheel of
Fortune" every night have lower incomes than those who do not. Should we then
conclude that television game shows decrease productivity? Or, by similar logic, should
we conclude that Thunderbird wine hurts productivity but Chivas Regal scotch helps it?
You may be wondering why the RTI study used the awkward variable of "marijuana-usedaily-for-a-month-ever" as an indicator of drug abuse. Good question. Actually, the RTI
researchers had information on current use (at least once in the last thirty days) of drugs -
- including cocaine, heroin; amphetamines and LSD as well as marijuana -- but they
could find no connection to decreased income. If Walsh really accepts the logic linking a
single month-long marijuana binge to decreased productivity, he must also conclude that
current use does not decrease productivity. But he shows no signs of doing so.
Walsh now admits that the RTI study "is based on assumptions that need additional
validation." One wonders why he hasn't passed that information on to Bush, Bennett,
representatives of the drug-testing industry, and others who continue to treat the "cost of
drug abuse to industry" as a scientifically established fact.
Anyway, Walsh says he has other evidence demonstrating the urgent need for workplace
testing. He and another NIDA official edited and a published a 340-page collection of
studies called: Drugs in the Workplace. When I interviewed Walsh recently, he drew my
attention to three studies in particular -- one done by the Navy and two by electric-power
utilities -- that he said showed that drug users make poor employees.
Let's start with the Navy study. The primary subjects were 500 recruits who tested
positive for marijuana in 1985 and were admitted anyway (those who tested positive for
any other illegal drug were rejected). Two-and-a-half years later the Navy had discharged
forty-three percent of those who had tested positive and only nineteen percent of those
who had tested negative during the same recruitment period. Sounds like former potheads
make lousy soldiers, right? Walsh even suggested to me that the lingering effects of preservice marijuana use may have been responsible. "We do know that it stays in the
system for a long time," he noted.