Spin in science writing -1: Observational study designs

Spinning in writing

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Spin in writing occurs all the time. And, it occurs when writing research papers too.

What is “spin in writing”?

It is a sort of word game that distorts the evidence shown by data. Sometimes, it may or may not be deliberate.

Contrary to the popular belief, research has shown that spin occurs irrespective of its funding source – industry-funded or public-funded.

This post discusses one aspect of spin in science writing. I use here a much-debated research topic and then explore expert suggestions to avoid occurring it again.

Hormone Replacement Therapy for coronary heart disease for those with post-menopausal symptoms

Background

Since the early 1980s, physicians have been prescribing hormones – estrogen and progesterone – for women to alleviate post-menopausal symptoms. During this time, some believed these hormones might also prevent coronary heart disease associated with the post-menopausal period. A group of interested researchers followed from 1976 to 1980 a group of 121,964 female nurses who took hormonal tablets. They collected their responses to a mailed questionnaire periodically during the study period. Their aim was to compare non-fatal and fatal heart attack rates between nurses who took and did not take the medications. The findings of their study appeared in the New England Journal of Medicine in 1985. You can read its abstract here.

Look closely at the last sentence of the abstract. The study authors claim that their “data support the hypothesis that the postmenopausal use of estrogen reduces the risk of severe coronary heart disease”.

The keyword here is “reduces”.

Can they make that claim?

The experts say “NO”

They should not have used the verb, “reduces”.

Why?

Because they have adopted an observational study design. The observational study designs do not warrant using “declarative” verbs. We can use only “descriptive verbs”.

The observational study designs provide us information about either associations or correlation between the study variables, certainly not its causative relationships. If we want to find out strong evidence for causative mechanisms we should adopt randomized controlled study designs. In other words, we can use active verbs such as “reduce” only with randomized study designs.

Declarative verbs and descriptive verbs

It is worth digging a little further about declarative and descriptive verbs. I found a very useful paper with regard to this subject. In 2017, two Austrian surgeons published a short paper describing the differences between declarative and descriptive verbs citing examples. I am using the same example of verbs and verbal phrases here because it is pretty comprehensive and very useful particularly for those whose English is not their primary language.

What are declarative verbs and verb phrases?

Some examples of declarative verbs and verbal phrases are shown below. The former ones declare some definitive action. The latter describes.

Declarative words and phrasesDescriptive words and phrases
Showare in favor
Demonstrateare in association with
Provebelieve
Establish bring forward
Causecarry, provide
Determine find, report, suggest
Result in get
Reduce have
increase/decreasehighlight
hold, underscore
identify, think, underlie
look, observe
maintain, place

About the verb “show”

In that paper, the authors caution us when using the verb, ” show” – it can either be used in a descriptive or declarative sense – and they suggest instead using the following verbs when the verb, “show” is required to use in its descriptive sense.

  • depict
  • exhibit
  • display
  • expose
  • reveal

Hedging verbs

There is another set of verbs called “hedging verbs or verbal phrases”. The following are examples of those.

  • This may account for
  • seems
  • appears
  • suggest
  • could support
  • indicate

As suggested in the paper, we should not use those to imply or define causation.

How should we use the adjective, “significant”?

I had this puzzle at the beginning of my career. In research papers, the word “significant” is used with its literal meaning as well as when discussing statistical findings; we write our findings either “statistically significant” or “statistically non-significant” based on the probability value (p-value). The paper suggests reserving the adjective the word with “statistically” to avoid confusion. Instead, the authors suggest the use of words such as “substantial” and “substantive” instead of the adjective “significant”.

So, now how should we write a statistically significant or non-significant finding from an observational study design?

The authors of the above paper suggest that we should write sentences such as follows:

  • A statistically significant was found …..
  • A is associated with a statistically significant increase (or a decrease) ….

“trend”

We can find this word in research papers and even in the abstracts commonly when the p-value is more than 0.05. The experts advocate not to engage in this practice particularly not to “imply or claim statistical significance”.

Correlate and agreement

And, the above verbs too should be reserved to discuss statistics because the “correlate” is used with Pearson r and spearman rank correlation statistical tests. Similarly, “X was in agreement with Y” too should be avoided because of Cohen’s “agreement” Kappa statistic.

Verb tense

The verb tense also matters; The above two editor surgeons claim that the past tense always is descriptive and the present tense is declarative. For example, X (intervention) decreased mortality” is descriptive and “X decreases mortality” declarative and implies causality.

However, the year 2002 reversed it all. The JAMA published a paper based on the findings from a randomized controlled design. According to the paper, the authors stopped the study prematurely due to exceeding the expected breast cancer risk. And, they found higher coronary heart disease and stroke risk too. This debate is still going on. I do not intend to delve into this conflict. My aim is to emphasize on choosing the most appropriate verbs that reflect the strength of evidence, based on the study design.

Those who are interested can read the following blog post that explains more about this subject written by Hilda Bastian:https://absolutelymaybe.plos.org/2016/03/17/how-to-spot-research-spin-the-case-of-the-not-so-simple-abstract/#:~:text=Research%20spin%20is%20when%20findings,message%20you%20want%20to%20send.

Author: Prasantha De Silva

A specialist in Community Medicine board-certified in Sri Lanka and a research analyst in Canada

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