13.6 Compiling tables of numerical summary information

Here are some tips for compiling tables of numerical summary information:

  • Round numbers appropriately (don’t necessarily use all decimals provided by software).
  • Place captions above tables.
  • In general, use no vertical lines and very few horizontal lines.
  • Align numbers in the table by decimal point when possible, for easier reading.
  • Ensure the table allows readers to easily make the important comparisons.

Example 13.12 (Tables for summarising data) Consider a study (Ejtahed et al. 2012) assessing the effects of probiotic and conventional yoghurt on blood glucose and antioxidant status in Type 2 diabetic patients. A randomised controlled trial (i.e., an experiment) collected data from 60 patients.

Compare the two numerical summary tables in Tables 13.6 and 13.7: Table 13.6 makes comparing the two groups easier, but Table 13.7 is the more conventional orientation (for practical purposes: fewer columns).
TABLE 13.6: Baseline characteristics of study participants. A superscript a indicates the data are summarised using means \(\pm\) standard deviation; a superscript b indicates the data are summarised using medians \(\pm\) IQR
Yoghurt Age\(a\) Weight (kg)\(a\) BMI\(a\) (kg/m\(2\)) Metformin/d\(b\) Glibenclamide/d\(b\)
Conventional (\(n=30\)) \(51.0 \pm 7.3\) \(75.42 \pm 11.28\) \(29.14 \pm 4.30\) \(2 \pm 1.25\) \(1 \pm 1\)
Probiotic (\(n=30\)) \(50.9 \pm 7.7\) \(76.18 \pm 10.94\) \(28.95 \pm 3.65\) \(2 \pm 1.25\) \(2 \pm 2\)
TABLE 13.7: Baseline characteristics of study participants. A superscript a indicates the data are summarised using means \(\pm\) standard deviation; a superscript b indicates the data are summarised using medians \(\pm\) IQR
Variable Conventional yoghurt (\(n=30\)) Probiotic yoghurt (\(n=30\))
Age\(a\) 51.00 \(\pm\) 7.32 50.87 \(\pm\) 7.68
Weight (kg)\(a\) 75.42 \(\pm\) 11.28 76.18 \(\pm\) 10.94
BMI (kg/m2)\(a\) 29.14 \(\pm\) 4.30 28.95 \(\pm\) 3.65
Metformin/d\(b\) 2 \(\pm\) 1.25 2 \(\pm\) 1.25
Glibenclamide/d\(b\) 1\(\pm\) 1 2 \(\pm\) 2
Think 13.11 (Sample differences) Do you think a difference exists between the mean BMI in the two groups in the population, based on Tables 13.6 and 13.7? Explain.

References

Ejtahed HS, Mohtadi-Nia J, Homayouni-Rad A, Niafar M, Asghari-Jafarabadi M, Mofid V. Probiotic yogurt improves antioxidant status in type 2 diabetic patients. Nutrition. 2012;28:539–43.