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 ± standard deviation; a superscript b indicates the data are summarised using medians ± IQR
Yoghurt Agea Weight (kg)a BMIa (kg/m2) Metformin/db Glibenclamide/db
Conventional (n=30) 51.0±7.3 75.42±11.28 29.14±4.30 2±1.25 1±1
Probiotic (n=30) 50.9±7.7 76.18±10.94 28.95±3.65 2±1.25 2±2
TABLE 13.7: Baseline characteristics of study participants. A superscript a indicates the data are summarised using means ± standard deviation; a superscript b indicates the data are summarised using medians ± IQR
Variable Conventional yoghurt (n=30) Probiotic yoghurt (n=30)
Agea 51.00 ± 7.32 50.87 ± 7.68
Weight (kg)a 75.42 ± 11.28 76.18 ± 10.94
BMI (kg/m2)a 29.14 ± 4.30 28.95 ± 3.65
Metformin/db 2 ± 1.25 2 ± 1.25
Glibenclamide/db 1± 1 2 ± 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.