Public Health Research and Epidemiology

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Unit PHR1: Research Skills (part I)

Module Overview / Unit PHR1 / Session 3

The Scientific Method

The objectives of this session are to:

  • Explain the scientific method in respect of the null hypothesis, alternative hypothesis and hypothesis-testing.
  • Understand the need for and process of citation in academic writing.
  • Summarise the main methods of disseminating information in today’s research environment.
  • Summarise a range of conventional journal article types and their structure.
  • Demonstrate appropriate formal writing skills in the planning and production of a journal manuscript, including academic style and structure (IMRaD, voice, tenses etc).

Watch

Please watch the video lecture for this unit - The Scientific Method and the Dissemination of Evidence

Exercise

1 - 2 - 3 - 4 - 5

We talked a bit about James Randi. His educational foundation offers a prize for proof of any ‘paranormal phenomenon’. You can see an interesting (and entertaining) TED Talk in the C-block.

Please have a look at the website for The James Randi Educational Foundation.

But let’s be a bit more serious. We’ve talked about hypotheses. The null hypothesis is the hypothesis that we want to reject (or in proper terminology, falsify – to indicate it is false). The null hypothesis is the hypothesis of no effect.

Indicate which of the following are null hypotheses:

Statement Is this a null hypothesis?
Yes | No
1

Tobacco consumption is not associated with increased incidence of carcinoma of the larynx.

Correct!
Incorrect!
2

Physical activity is associated with no increased risk of cardiovascular death.

Correct!
Incorrect!
3

A reduction in particulate matter from combustion engines is associated with a reduction in the frequency and severity of asthmatic attacks for people living within 50 metres of major highways and a history of asthma.

Correct!
Incorrect!

Indicate an alternative hypothesis to statements 1 and 2 above.

Statement Answer
1
Tobacco consumption is associated with an increased incidence of carcinoma of the larynx.
2
Physical activity is associated with a decreased risk of cardiovascular death.

About tense.

In the following extracts, please indicate whether the correct tense is used:

Extract Is this the correct tense?
Correct | Incorrect
1

INTRODUCTION - Staff satisfaction is associated with hospital standardized mortality ratios.

The present tense is used for established evidence. The sentence is therefore correct.
The present tense is used for established evidence. The sentence is therefore correct.
2

INTRODUCTION - Costelloe, et al show that antimicrobial resistance is not considered important by hospital doctors.

The present tense is used for established evidence, but when used with a named researcher, the past tense should be used. Therefore this sentence is not correct. It should read: “Costelloe et al showed that antimicrobial resistance is not considered important by hospital doctors.” Note that the assertion remains in the present tense.
The present tense is used for established evidence, but when used with a named researcher, the past tense should be used. Therefore this sentence is not correct. It should read: “Costelloe et al showed that antimicrobial resistance is not considered important by hospital doctors.” Note that the assertion remains in the present tense.
3

METHODS - We collected data from 250 hospitals.

The past tense is used for the Methods section. This sentence is therefore correct.
The past tense is used for the Methods section. This sentence is therefore correct.
4

METHODS - Data from 250 hospitals were collected.

The past tense is used and is therefore correct. However instead of the active voice, the passive voice is used. Journals will generally have a particular choice of voice, but either can be used for reports.
The past tense is used and is therefore correct. However instead of the active voice, the passive voice is used. Journals will generally have a particular choice of voice, but either can be used for reports.
5

RESULTS - In our study, aspirin is associated with a decreased risk of occlusive stroke.

The Results should be stated in the past tense, and therefore this sentence is incorrect.
The Results should be stated in the past tense, and therefore this sentence is incorrect.
6

RESULTS - In our study, a decreased rate of occlusive stroke was observed in the cohort of patients receiving aspirin therapy.

This is correct: the past tense is used in the Results section.
This is correct: the past tense is used in the Results section.
7

DISCUSSION - Our evidence supports the findings of previous groups.

This is correct: the present tense is used in the Discussion.
This is correct: the present tense is used in the Discussion.
8

DISCUSSION - An important limitation of our study is that we were unable to account for response rate…

This is correct: the statement is in the present tense but refers to a limitation in the past tense. Conversely, the present tense could be used for both and would also be correct.
This is correct: the statement is in the present tense but refers to a limitation in the past tense. Conversely, the present tense could be used for both and would also be correct.
About structure.

The BMJ gives comprehensive advice> as to the types of articles it accepts.

For a research article, look at the sections they require.

Checklists for reporting research.

Journals are increasingly requiring that a checklist is completed alongside a manuscript. The checklists ensure that authors are providing all the information needed to adequately report their work. Historically authors have failed to report important aspects of their trial design – for example how subjects were randomised, or how many of their subjects were lost to follow up. Such gaps can affect how valid a trial is and how prone it might be to bias.

For the reporting of trials, the CONSORT guidelines are used. You can find out more about the CONSORT guidelines by visiting their website, and you can also view the checklist.

There are equivalent checklists for alternative types of research including

  • PRISMA for Systematic Reviews and Meta analyses
  • STROBE for Observational Studies

We'll come back to these checklists later on in the course, when we cover trial design.

Conclusion

Please listen to the following conclusion to this session.

Further resources

James Randi at TED

The Scientific Method. In Our Time, January 2012, BBC Radio 4

BMJ: References that anyone can edit

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