TIP
Use common sense to report final values according to the correct rules of rounding – don’t just report what the computer tells you. This principle – using your common sense to interpret computer output – will come up again and again throughout this book.
TABLE 1.3 Impact of Rounding Styles on Mean Value
| Original Value | Correctly Rounded to Nearest Even Digit | Incorrectly Rounded (Always Upward) |
| 163.5 | 164 | 164 |
| 164.5 | 164 | 165 |
| 165.5 | 166 | 166 |
| 166.5 | 166 | 167 |
| Average = 165 | Average = 165 | Average = 165.5 (rounded = 166) |
1.8 READING
The concepts which underlie research design and statistics set out in this book may be very different from any that you have had to think about. Persistence will bring rewards, however, even if the topics seem difficult at first.
Very often, one author's treatment of a topic will seem totally incomprehensible, while another's will seem crystal clear. Below, therefore, is a list of books to which you might like to refer – try at least two on the same topic if you are having difficulty grasping a particular idea. Don’t worry about the publication dates – the approaches to basic statistics have not changed for the last few decades. The volumes cited use examples from medicine rather than nutrition and dietetics, but the statistical principles remain the same.
The books marked with an ‘*’ are particularly highly recommended. Note that a number of these texts are now available as e‐books, usually at a substantially reduced price compared with the hard copy.
TABLE 1.4 Impact of Screening for Breast Cancer on 5‐year Mortality in 62 000 Women
| Cause of Death | |||||
| Breast Cancer | All Other Causes | ||||
| n | n | Rate/1 000 | n | Rate/1 000 | |
| Screening group | |||||
| Examined | 20 200 | 23 | 1.1 | 428 | 21 |
| Refused | 10 800 | 16 | 1.5 | 409 | 38 |
| Total | 31 000 | 39 | 1.3 | 837 | 27 |
| Control group | 31 000 | 63 | 2.0 | 879 | 28 |
* Armitage P, Berry G, Mathews JNS. Statistical Methods in Medical Research. 4th edition. Blackwell Science. Oxford. 2001. Very thorough and wide‐ranging, with excellent explanations of the mathematics behind the statistics. Highly recommended.
* Bland M. An Introduction to Medical Statistics. 4th edition. Oxford University Press. 2015. Good, basic introduction, wide ranging, with lots of useful examples including SPSS. Might be a bit difficult for beginners, as he tends to jump straight in without too much underlying explanation.
* Bowling Ann. Research Methods in Health. 4th edition. Open University Press. Buckingham. 2014. This text provides an excellent overview of issues in both quantitative and qualitative research. Together with Ann Bowling's other text (‘Measuring Health’, 4th edition, McGraw Hill Education, 2017), it provides a practical and straightforward guide to research design for the health sciences.
Campbell MJ, Machin D, Walters SJ. Medical Statistics: A Textbook for the Health Sciences (Medical Statistics). 4th edition. Wiley‐Blackwell. Chichester. 2007. A comprehensive text, the book has lots of ‘common sense’ tips and useful comments sprinkled liberally throughout.
* Campbell MJ. Statistics at Square One. 11th edition. BMJ Books. 2009. Useful little ‘cookbook’, good for quick reference to remind you of the underlying statistical formulae, but not very good about explaining the principles underlying the tests or why they work as they do.
Campbell MJ. Statistics at Square Two. 2nd edition. BMJ Books. 2006. This is a useful follow‐on to Statistics at Square One. It explores more complex statistical analyses involving multiple variables and complex study designs.
Freedman D, Pisani R, Purves R. Statistics. 4th edition. Norton. London. 2014. Basic and very readable text. May at times seem long‐winded, but lots of detailed examples and useful exercises (with answers).
Glantz SA. Primer of Biostatistics. 7th edition. McGraw‐Hill. London. 2012. First rate text, very clear descriptions of tests with medical examples and problems for solving.
Corder GW, Forman DI. Nonparametric Statistics: A Step‐by‐Step Approach. 2nd edition. Wiley. 2014. Very good at explaining the fundamentals of nonparametric statistics.
* Juster, Norton. The Phantom Tollbooth. Harper Collins. New York. 2008. Illustrations by Jules Feiffer. A wonderful allegory of scientific thinking concerning two kidnapped Princesses: Rhyme and Reason. The illustrations by Jules Feiffer perfectly complement Milo’s struggle to make sense of the world. The ideal fantasy for when you're fed up with statistics.
Mead R, Curnow RN and Hasted A (editor). Statistical Methods in Agriculture and Experimental Biology. 3rd edition. Chapman and Hall CRC Press. London. 2002. The authors worked in the Applied Statistics Department of the Food Research Institute at Reading, so the examples are geared towards food science.
Moser CA and Kalton G. Survey Methods in Social Investigation. 2nd edition. Heinemann Educational. London. 1985. Detailed and practical advice on survey techniques and design. Nonmathematical. A classic.
* Norman GR and Streiner DL. Biostatistics: the Bare Essentials. 4th edition. People’s Medical Publishing House. USA. 2014. Clear, funny, and irreverent. Goes into the lower reaches of the upper echelons of statistics (i.e. covers the basics plus some of the more advanced stuff).
* Riegelman R. Studying a Study and Testing a Test: How