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.