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Table 1 Characteristics of surveys showing departure from a normal distribution (Shapiro–Wilk test, p < 0.05) and effect of transformation and smoothing on specific characteristics (N = 533)

From: Is Middle-Upper Arm Circumference “normally” distributed? Secondary data analysis of 852 nutrition surveys

Surveys failing Shapiro–Wilk test (p < 0.05) N = 533 (62.6 %) N (%) N (%) with “normal” distribution after transformation or smoothing
Box-Cox Spline Loess
All surveysa 533 (100) 301 (56.5) 318 (59.7) 304 (57.0)
By key survey characteristics     
Skewedb 183 (34.3) 113 (61.7) 81 (49.4) 89 (48.6)
Non-normal kurtosisc 196 (36.8) 62 (31.6) 137 (69.9) 139 (70.9)
Skewed and non-normal kurtosisb, c 70 (13.1) 23(32.9) 41 (58.6) 43 (61.4)
Large design effect (>3) 164 (30.8) 86 (52.4) 81 (49.4) 92 (56.1)
High digit preference (score < 0.75) 294 (55.2) 143 (48.6) 170 (57.8) 178 (60.6)
Large sample size (n > 900) 204 (38.3) 122 (59.8) 95 (46.6) 101 (49.5)
  1. aShapiro–Wilk test (p < 0.05); b D’Agostino test (p < 0.05); c Anscombe–Glynn test (p < 0.05)