What Did the Report Say!? Sampling 101

Most people have taken a statistics class at some point in their school career, but the reality is that

after school the statistical learning often stops. When drug and alcohol testing companies like CMM

Technology mention random testing, there is a good chance many workers have forgotten what the

statistical method entails.

Employers, on the other hand, understand what random testing means. However, the ones who try to

stay current on the latest research on drugs and alcohol are bound to run into terms that have little

meaning. Understanding the basics of sampling gives employers the tools needed to intelligently

respond to staff questions, whilst recognising commonly used research terms makes the information

in written materials easier to assimilate.

No Head Shaking

First things first: When a company says it will randomly test employees for drugs and alcohols there

are certain principles assumed to be at work.

There is a definable method for selection of those to be testing

The selection method is objective, eliminating personal biases

There an equal probability that each person in the defined group of people identified for

testing will be selected

There is an independent chance a person will be selected

The employer will not interfere in the selection process so that it remains random

The statistical population is the group targeted for random testing. It may be a department, the

entire organisation, job titles designated as high-risk positions, and so on. Stratified random

sampling is a term used to divide the entire population of employees into smaller groups based on

shared attributes, like high risk job duties. The smaller groups are called strata. The random

sample then draws a number of people for testing that is proportional to the stratum’s size when

compared to the population.

Terms, Terms, and More Terms

Random sampling can actually be applied in a variety of ways. There is random sampling, simple

random sampling, cluster sampling, spatial sampling, quota sampling, and so on. However, when

employers are reading research reports they will also run into terms like those used in this

sentence:”Respondent driven sampling, traditional snowball sampling and street outreach

methods were used to recruit heroin and amphetamine injectors from one outer-urban and two

inner-urban regions of Melbourne, Australia.”

This is a classic example of how critical information can get lost in a sea of words. Though the term

“street outreach methods” is fairly obvious as to what it means, the term “snowball sampling”

is unfamiliar to most. Snowball sampling is also called referral sampling or chain sampling because

it is a method for identifying program participants by asking research participants for referrals. It is

a non-probability sampling technique and no relationship to random sampling.

Respondent-driven sampling is a statistical method for combining snowball sampling with a

mathematical model that compensates for the non-random sampling method. These terms and more

are regularly used in articles discussing research on drug and alcohol addiction. Understanding the

terms makes the information provided intelligible.

Catching Terms

There is general agreement that workplace data collections concerning drugs and alcohol are

limited in terms of breadth and quality. It is impossible to understand the full extent of the problem

until there is adequate data to assess. However, all the data that has been collected to date by

various agencies and organisations all bolster the belief that workplace substance use is common,

thus supporting the need for random alcohol and drug testing.

Terms get tossed about whilst people shake their heads in agreement as if they understand what is

being discussed. They do not know what the terms mean but are unwilling to acknowledge they do

not know, or they give up trying to stay informed. Mediscreen uses drug screening methodologies

and procedures that reflect the best information obtained from toxicologists and industry experts.

Coupled with a truly random selection of screening subjects, employers have the assurance that the

right steps are being taken to minimise workplace drug and alcohol use.

This article has been taken from :

http://www.mediscreen.net.au/what-did-the-report-say-sampling-101/