120 workers were chosen at random from a company. Half of them were… Step by Step

Step by step

The question

Question: 120 workers were chosen at random from a company.

Half of them were chosen at random to take a short break each hour.

The break group made fewer mistakes.

What can the study say?

1 Two questions

To judge a study, we ask two questions.

How were the workers picked?

And how were the groups made?

2 How they were picked

The story says the workers were chosen at random from the company.

So: yes.

At random means all the workers in the company had the same chance to be picked.

So the group is a fair small copy of the whole company.

random: all workers in the company had the same chance

So what we find can be used for the whole company: true for all workers in the company.

3 How the groups were made

The workers were chosen at random to take a short break each hour.

So: yes.

Chance made the groups, not the workers.

So the two groups are alike, except for the break.

random groups: alike, except for the break

So the difference comes from the break: the break causes it.

Careful!

Only for the company they were picked from.

Not for all workers everywhere.

Careful: not true for all workers everywhere ✗

4 What the study can say

So the study can say: for all workers in the company, the break causes this.

= causes it, for the whole company

5 Check

Let's check with the story.

The first sentence says: chosen at random from the company.

That matches.

"chosen at random from" → all the company

The second sentence says: chosen at random to take a short break each hour.

That matches too.

So the answer is right!

"chosen at random to" → causes

Let's look back.

First: two questions.

Then: how they were picked.

Then: how the groups were made.

Then: what the study can say.

Last: check.

Answer