hypothesis testing

2. Understanding Standards
Event
Higher Statistics Award

3. Hypothesis Testing
David Young
Department of Mathematics & Statistics
University of Strathclyde
NHS, Greater Glasgow and Clyde

4. Overview
Welcome to the University of Strathclyde
 introduction to SQA level 6 Statistics Award
(SQA Home > National Qualifications > Subjects > Statistics Award
(SCQF level 6)
 how statistics can answer important questions
 practical sessions using Minitab and/or R

5. What is statistics …?
 statistics is the science of collecting, analysing,
presenting and interpreting data
 it enables the objective evaluation of research
questions of interest
 it provides the means to weigh up how much
evidence the collected data provide for and against
the research hypothesis of interest
 statistics are available on almost every aspect of
daily life

6. 2014 – the year of the selfie
 millions are shared each and every day across all the
major social media platforms
 according to data from Samsung,
selfies make up almost one-third of all
photos taken by people aged 18-24
 Facebook, WhatsApp, Twitter,
Instagram and Snapchat bearing the brunt of that load
 Link – http://www.adweek.com/digital/selfie-generation/
 Twitter’s most retweeted post of all time …
 Twitter’s most retweeted post of all time
 …

7. Use this slide for large images,
graphics or tables.

8. Addressing important questions
 Can you get diabetes from eating too much sugar?
 What are the side effects of too much vitamin D?
 Is smartphone addiction a real phenomenon?
 Does eating turkey at Christmas make you tired?
 Does vitamin C make you look younger?
 Is paracetamol better than codeine for treatment of
pain?
 ‘Two heads are better than one’.
 Statistics can be used to answer such
questions

9. Not always a clear answer …
 turkey makes you tired because it’s loaded with
tryptophan
 tryptophan is a pre-cursor to serotonin which is a
mood modulator, inducing relaxation and supporting
sleep
 tryptophan alone does not make you tired
 combining tryptophan with carbohydrates does
 it is not the turkey that’s causing Christmas
sleepiness, it’s the turkey plus the cranberries, rolls,
and pie
 turkey actually has less tryptophan than
chicken

10. Drug development
 pharmaceutical companies have to
gather data on drug performance
 a drug cannot be used commercially until the
company have produced evidence of efficacy and
safety
 statistical tests (known as hypothesis test) can be
used to gather this evidence

11. Omeprazole
 Omeprazole (Prilosec, Zegerid) belongs to a
group of drugs called proton pump inhibitors
 it decreases the amount of acid produced in the
stomach
 Omeprazole is used to treat symptoms of
gastroesophageal reflux disease (GERD) and other
conditions caused by excess stomach acid
 common side effects may include: stomach pain, gas,
nausea, vomiting, diarrhoea or headache
 https://www.drugs.com/omeprazole.html

12. Statistics and Probability
 statistical analysis considers the probability of an
event being due to chance
 can never be 100% certain for example that one
treatment is better than another
 can say mathematically how sure we are that a result
is true

13. Probability
 hypothesis: all dogs can bark
 how would you prove this?
 data has to be gathered to give evidence for or
against the hypothesis
 a hypothesis test has to be performed

14. Pain assessment score

15. Hypothesis Testing

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24. Hypothesis Testing

25. Hypothesis Testing

26. Hypothesis Testing

27. Interpretation
 If the difference was not due to chance why did it
happen?

28. Interpretation
 If the difference was not due to chance why did it
happen?
 When is this claim valid?

29. Interpretation
 If the difference was not due to chance why did it
happen?
 When is this claim valid?
 What are the consequences of getting it wrong?

30. Additional Points
 errors in hypothesis testing – p<0.01!
 null and alternative hypotheses
 cranberry juice – randomisation
http://www.ncbi.nlm.nih.gov/pubmed/22961092

31. Additional Points
 double blind studies
 http://www.theguardian.com/society/2005/jan/17/health
.medicineandhealth
 placebo trials
 comparison of baseline characteristics
 intention-to-treat and per-protocol
– weight loss example
 tests for correlation, regression and
normality testing

32. Two heads are better than one …?
 study design?
 what were the rules for doing the quiz?
 randomisation?
 double blind?
 how many participated – why is this important?
 who marked?
 are you satisfied that the groups were comparable?

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