. 2022 Feb 17;5(2):e2143388. doi: 10.1001/jamanetworkopen.2021.43388

Table 2. Coefficients From Preregistered Linear Probability Model Regression Results Comparing Reserved and Available Conditions.

Variable	Effect, B coefficient (SE)
Variable	Model 1: unadjusted (n = 6726)	Model 2: adjusted (n = 6726)	Model 3: with replied Y (n = 6726)
Reserved condition	0.014 (0.012)	0.010 (0.010)	−0.013 (0.009)
Replied Y to text	NA	NA	0.496 (0.010)^a
Penn Medicine site	NA	0.095 (0.011)^a	0.023 (0.010)^b
Age (centered)	NA	0.002 (0.0003)^a	0.002 (0.000)^a
Race and ethnicity
Asian	NA	−0.008 (0.034)	0.026 (0.029)
Black	NA	−0.059 (0.014)^a	−0.001 (0.012)
Hispanic	NA	−0.033 (0.023)	−0.009 (0.020)
White	NA	1 [Reference]	1 [Reference]
Other^c	NA	−0.012 (0.028)	0.007 (0.024)
Male sex	NA	0.018 (0.010)^d	0.016 (0.009)^d
Clinician
Physician	NA	0.002 (0.018)	−0.001 (0.015)
Physician assistant	NA	0.003 (0.024)	0.011 (0.020)
Resident	NA	−0.047 (0.027)^d	−0.050 (0.024)^b
Nurse practitioner	NA	1 [Reference]	1 [Reference]
Influenza vaccine last year	NA	0.266 (0.010)^a	0.148 (0.009)^a
Time since study start (centered)	NA	−0.003 (0.0003)^a	−0.001 (0.0003)^a
Time squared (centered)	NA	−0.0000008 (0.000002)	−0.0000003 (0.000002)^d
Constant	0.332 (0.008)^a	0.181 (0.020)^a	0.125 (0.017)^a
Adjusted R²	0.0001	0.275	0.462

Abbreviations: NA, not applicable; Y, yes.

^{^a}

P < .001.

^{^b}

P < .05.

^{^c}

Includes patients whose race and ethnicity was identified as “other” in the electronic health record.

^{^d}

P < .10.