What is 'critical thinking'?


To explain ‘critical thinking’ it’s easiest to give an example:

If I was the health minister in Kenya, and I wanted to develop a policy on Tuberculosis, I would need to look at the evidence before I make any policy decisions. I’d like to know the information on:

  • the scale of the problem, and whether TB rates were higher in certain population groups or regions
  • the social, environmental and biological factors that influence TB transmission
  • evidence about what interventions are successful at preventing and managing TB.

Not all this information might be routinely collected or readily available when I’m writing the policy. So I have to make a judgement about the type of information that is available, and the quality and accuracy of it. That’s where being critical is important, so that you can chose information sources critically.


How can I chose my information sources critically?


When reviewing information (whether it published or unpublished information), it’s important to be critical about the quality of the information, and to consider ‘how’ it might be biased by asking yourself:

  • How was the information collected? Was it a robust method?
  • Who produced the information – is there any conflict of interest?

Depending on how the information was collected, and who it was collected by, we might value it in a different way.


How evidence is collected and valued


If we wanted to measure the rate of TB in Kenya and look at measures to reduce TB, we need to search for published and unpublished data that give us accurate information. There are different ways of collecting evidence (different research methods) and some methods are valued more highly in the scientific world, as the research process is more robust.

Here are some examples of the different research methods (these are not based on actual research, but are hypothetical research studies).

If we wanted to measure the rate of TB in Kenya and look at measures to reduce TB, we might consider the following sources of information, which are ordered according to their ‘scientific’ value:

Anecdotal evidence: ‘I’ve noticed that there’s a lot of people in Nairobe, attending my clinic with TB, particularly men’

Case reports: Community health workers in several different villages have recorded a high rate of TB in male truck drivers (diagnosis of TB based on symptom chart)

As you will know from a number of the modules in Peoples-uni, these first two sources of information above are notoriously unreliable sources of evidence! Those mentioned below are much higher in the hierarchy of evidence.

Cross-sectional surveys: mortality from TB was measured during a survey in different villages in Kenya, by speaking to relatives of the deceased and doing a verbal autopsy. TB mortality rates were higher in males than females.

Case-Control Studies: Patients with multi-drug resistant TB are more likely to work in low paid, unskilled jobs compared to patients with non-resistant TB

Cohort Studies: All mothers attending antenatal clinic in Nairobe in 1995 were followed up for 12 years for signs of TB. The risk of developing TB was higher in mothers who had more than 2 children, were unemployed, etc

Randomised Control Trials: patients with TB were randomised to either receive the intervention (Directly Observed Therapy) or the control programme (TB treatment prescribed by the local hospital with no follow up). The study showed that patients are more likely to have successful clinical outcomes when prescribed under Directly Observed Therapy, than people receiving unsupervised treatment.

The research methods above give you ‘quantitative’ evidence, however these methods cannot always help you understand people’s attitudes, feelings and behaviours and how these influence their health e.g:

Qualitative Research– interviews and focus groups with community health workers suggest that lack of access to transport is a barrier to patients accessing TB clinics for treatment

So when you’re reading an article, think about the way in which the information was collected (is it a robust research method?) and also how well the research was conducted (just because the evidence is from a randomised control trial does not mean that the research was well conducted).


What critical thinking isn't!


Critical thinking is not just forming opinions, it is putting forward an argument where the evidence has been weighed up.

For example, in a discussion about TB, people may have lots of strong opinions about the associations of TB.

..."you only get TB if you are poor...."people with TB have caught it through immoral behaviour".."everyone with TB is infectious..".."everyone with TB has HIV..."

Or, what should be done about it..."isolate people with TB..."..."patients with TB should be separated from their children..."

Of course, there may be some truth in these opinions and they may help us understand the dynamics of the problem, however, they shouldn't be accepted at face value. In order to get at the roots of a public health issue, it is important to recognise your own personal opinions so they don't bias how you will search for (and judge) evidence on that issue. A critical thinker recognises their own opinions and holds them aside while they weigh up the evidence regarding a potential preventative intervention, so that they can clearly see whether it would be effective or not.

When you write on the discussion forum (or in an assignment) it’s best to acknowledge your own opinions, and to tell your readers the source of your information. The comments above are anecdotal evidence and so you should state on the discussion forum: ‘in my opinion’ or ‘local leaders believe’ ’ that you only get TB if you are poor. This is so that the readers can judge the value of that comment. This anecdotal evidence may then be backed up by more robust evidence that demonstrates from a cross-sectional survey that TB rates are higher in people living in deprived areas.

Being 'critical' at Masters level

So how do I translate this into practice, whilst reading and writing academically, and also in my everyday job?

Reading critically

You might want to look at this web site from Dan Kurland to explore some ideas about what is critical reading and critical thinking – his examples are not from Public Health: http://www.criticalreading.com/critical_reading_thinking.htm#linkd
The site nicely summarises critical thinking as: “Critical thinking includes a complex combination of skills. Among the main characteristics are the following:


We are thinking critically when we

  • rely on reason rather than emotion,
  • require evidence, ignore no known evidence, and follow evidence where it leads, and
  • are concerned more with finding the best explanation than being right analyzing apparent confusion and asking questions.


We are thinking critically when we

  • weigh the influences of motives and bias, and
  • recognize our own assumptions, prejudices, biases, or point of view.


We are thinking critically when we recognize emotional impulses, selfish motives, nefarious purposes, or other modes of self-deception.



We are thinking critically when we

  • evaluate all reasonable inferences
  • consider a variety of possible viewpoints or perspectives,
  • remain open to alternative interpretations
  • accept a new explanation, model, or paradigm because it explains the evidence better, is simpler, or has fewer inconsistencies or covers more data
  • accept new priorities in response to a reevaluation of the evidence or reassessment of our real interests, and
  • do not reject unpopular views out of hand.


We are thinking critically when we

  • are precise, meticulous, comprehensive, and exhaustive
  • resist manipulation and irrational appeals, and
  • avoid snap judgements.


We are thinking critically when we

  • recognize the relevance and/or merit of alternative assumptions and perspectives
  • recognize the extent and weight of evidence.


Here's an example to illustrate how critical thinking and reading go hand in hand:


Being critical in practice: the process

Imagine you are a health professional in Kenya. You are asked to decide whether you think a health education program for TB is a useful intervention in your country to help control TB.

A colleague shows you this news article: http://medilinkz.org/news/news2.asp?NewsID=9992

"Kenya - TB Ravages Community As Medics Blame Culture - Wednesday, March 23, 2005

...Medics attribute the prevalence of the deadly disease to ignorance and most of all, the lifestyle of the local communities."

After reading this article, he/she thinks that there is enough evidence to suggest that there is a strong need to set up a health education program to change cultural beliefs about TB.

However, as a critical thinker, you decide that although the above article gives professional opinions, you need to make sure you can be confident about the quality of research on which this article is based. Some of the questions you ask include:

-Does this article reference the original research?
-Can I look at the original research?
-Who conducted the research?
-How was the research carried out?
-Where was the study done?
-Is it really applicable to my setting?

As you don't have the answers to all of these questions, you realise that you need to read a bit more widely to find more authoritative reports.

Searching further, you come across this peer-reviewed journal article, which is an example of qualitative research:

"From their own perspective. A Kenyan community’s perception of tuberculosis...TB control could improve significantly if more consideration were given to the health culture of the population..." https://www.ncbi.nlm.nih.gov/pubmed/9294551

Reading this article you can answer the above questions more confidently. This research article contains more concrete evidence that a health education program intervention may be of benefit. It also gives lots of other useful references for you to look at. However, you are still not sure if you have enough high quality evidence to decide whether health education could help control TB in Kenya.

Searching further, you find a systematic review that suggests that health education doesn't have a clear cut benefit in helping patients with TB adhere to their medication: http://www.bmj.com/cgi/content/full/315/7120/1403

"Systematic review of randomised controlled trials of strategies to promote adherence to tuberculosis treatment......What the independent effect of health education is on adherence is difficult to determine from existing trials."

Now, you consider that you may need to re-evaluate your initial perspective in the light of this new research evidence. Your search for the evidence continues. In this way, you continue reading and then weighing up the evidence for and against, until you feel confident that you have reached the point at which you can put forward a reasoned argument for your viewpoint.

Writing critically (assignments or discussion forums)

Working or living in Kenya, you will have direct experience of factors that influence health. However, sometimes it can be frustrating when there is little published research, which is based in Kenya and which accurately measures health or evaluates the impact of interventions. In this situation we have to discuss what evidence is available, and the potential disadvantages and gaps in this data. We can also look for evidence produced in other countries which might be applicable in Kenya.

It’s important that I reflect on the quality of the information when I present this to others, so that the people reading my work can also judge the quality of the information. For example, I might discuss the potential bias with the information:

Example of a good discussion forum message (completely hypothetical- not based on true situation):

There is no routine system for surveillance of TB in Kenya. TB prevalence rates have been recorded using cross-sectional surveys, and report a rate between 10-15% (insert reference). However, these surveys are mainly involving the male population in Nairobe, and therefore prevalence rates may be different in the female population and in rural areas. The cross-sectional surveys do not include active case finding, rely on self-reported symptoms and are therefore likely to underestimate the true prevalence of TB.

Dalghren and Whitehead outlined the array of social, environmental, political and individual factors that influence health (ref). TB is an infectious disease, and transmission of the mycobacterium is increased between humans when there is overcrowding, poor nutrition and high rates of HIV (insert ref). The WHO indicators for health in Kenya (insert ref) indicate that Kenya has high rates of poverty, overcrowding and poor nutrition. HIV prevalence is estimated between ? and ?%, measured through antenatal clinic screening (insert ref).

I believe that interventions to reduce the prevalence of TB should focus on each of the factors that influence disease prevalence, outlined my Dalghren and Whitehead. However, in my opinion, current policies to tackle TB in Kenya are focused on the treatment of TB. There is strong evidence to suggest that overcrowding and poverty are associated with higher rates of TB prevalence, however these issues are difficult to address through health system funding. There is strong evidence from randomised controlled trials in other countries (ref) to suggest that patients receiving Directly Observed Therapy have better treatment outcomes. However, there are insufficient health care workers in Kenya to deliver an effective DOT programme.

Critical thinking in the assignments.

You will note that in the 'criteria for a pass' in the Student Handbook, one of the assessment criteria is: The assignment should be satisfactory in its structure, evidence of critical thinking, and use of references. So it is worth making sure that the assignment you submit does reflect some of the issues discussed here.

Another resource you might find useful

Extending and developing your thinking skills from the Open University is worth reading -  please focus on: Section 6: asking questions; Section 8: critical appraisal - activity 17-19; Section 9 - activity 26-28.


For more on our academic study and writing skills resources library and courses, click here (requires login).