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Table 3 The discriminative power of patient experience surveys for different patient groups and quality aspects in unadjusted and adjusted models, accompanied by the sample sizes required to detect differences between providers reliably.

From: The discriminative power of patient experience surveys

  Empty model Adjusted model
          95% expected range of provider scores Required sample size per provider Required number of patients to be approached per providerc
  Variance providersa Variance individualsb ICC Variance providersa Variance individualsb ICC Mean SD providers lower limit upper limit range reliability = .70 reliability = .80 reliability = .70 reliability = .80
Doctor's communication                
   Hip or knee surgery (n1 = 43; n2 = 1462)c 0.0133 0.2955 0.043 0.0100 0.2818 0.034 3.44 0.10 3.24 3.64 0.40 65 112 87 150
   Varicose veins (n1 = 20; n2 = 2189) 0.0049 0.2118 0.023 0.0041 0.2040 0.020 3.62 0.06 3.49 3.75 0.26 117 200 190 325
   Cataract surgery (n1 = 55; n2 = 4021) 0.0035 0.1943 0.017 0.0033 0.1913 0.017 3.58 0.06 3.46 3.70 0.23 134 230 187 321
   Spinal disc herniation (n1 = 20; n2 = 1574) 0.0025 0.4125 0.006 0.0015 0.4020 0.004 3.52 0.04 3.44 3.60 0.16 614 1053 1452 2489
Change in physical functioning                
   Hip or knee surgery (n1 = 43; n2 = 1345) 0.0046 0.3168 0.014 0.0038 0.3105 0.012 2.50 0.06 2.38 2.63 0.24 193 331 258 442
   Varicose veins (n1 = 20; n2 = 1663) 0.0047 0.2117 0.022 0.0044 0.2100 0.020 2.46 0.07 2.32 2.59 0.26 112 192 181 310
   Cataract surgery (n1 = 55; n2 = 2982) 0.0003 0.1675 0.002 0.0002 0.1653 0.001 2.56 0.01 2.54 2.59 0.05 2516 4313 3494 5990
   Spinal disc herniation (n1 = 20; n2 = 1592) 0.0022 0.2720 0.008 0.0010 0.2560 0.004 2.43 0.03 2.37 2.49 0.13 569 975 1355 2322
Global rating                
   Hip or knee surgery (n1 = 43; n2 = 1496) 0.0332 1.8371 0.018 0.0215 1.7036 0.012 8.36 0.15 8.07 8.65 0.59 185 317 247 423
   Varicose veins (n1 = 20; n2 = 2169) 0.0952 1.7139 0.053 0.0915 1.6076 0.054 7.92 0.30 7.32 8.52 1.21 41 70 67 114
   Cataract surgery (n1 = 55; n2 = 3967) 0.0417 1.7341 0.023 0.0396 1.6791 0.023 7.75 0.20 7.35 8.15 0.80 99 169 138 236
   Spinal disc herniation (n1 = 20; n2 = 1590) 0.0486 2.4523 0.019 0.0450 2.3155 0.019 7.42 0.21 7.00 7.84 0.85 120 206 284 487
Recommendation to others                
   Hip or knee surgery (n1 = 43; n2 = 1497) 0.0076 0.3556 0.021 0.0063 0.3424 0.018 3.58 0.08 3.42 3.74 0.32 126 217 168 289
   Varicose veins (n1 = 20; n2 = 2154) 0.0182 0.3900 0.045 0.0170 0.3738 0.043 3.34 0.13 3.08 3.60 0.52 51 88 84 143
   Cataract surgery (n1 = 55; n2 = 4003) 0.0111 0.3055 0.035 0.0108 0.3008 0.035 3.41 0.10 3.20 3.62 0.41 65 112 91 156
   Spinal disc herniation (n1 = 20; n2 = 1564) 0.0160 0.5157 0.030 0.0146 0.4986 0.028 3.16 0.12 2.92 3.40 0.48 80 137 188 323
  1. a Variances in bold are significant (p < .05)
  2. b The significance of variances at the level of individuals is not reported
  3. c Derived from the required sample size and the response rate (hip or knee surgery (75%), varicose veins (62%), cataract surgery (72%), spinal disc herniation (42%))
  4. d n1 denotes the number of healthcare providers, n2 denotes the total number of patients