On-Line Appendix A; Bivariate Regressions
First–time Voters:
Foreign Nationals
Other first generation immigrants
Native Norwegian s Below Age 30
Native
Norwegian At Age 30 and Above SMS
text message
2.93 (.50)
2.73 (.34)
4.58 (.48)
.96 (.20)
Constan t
21.68 (.23)
41.32 (.23)
45.78 (.22)
72.66 (.08)
N 41,400 83,988 66,086 389,107
R- squared
.001 .001 .001 .000
On-Line Appendix B; Bivariate regressions weighted by household size (IPW analysis)
First–time Voters:
Foreign Nationals
Other first generation immigrants
Native Norwegian s Below Age 30
Native Norwegian At Age 30 and Above SMS text
message (ATE)
2.84 (.52)
2.71 (.34)
4.61 (.48)
1.08 (.19)
SMS control
21.69 (.23)
41.32 (.23)
45.30 (.22)
72.59 (.08) Househol
d size
-.86 (.22)
-.009 (.00)
.10 (.02)
.11 (.00)
N 41,400 83,988 66,086 389,107
The experiment randomly selected one individual from each household to receive a text message. Doing this may have increased the probability of receiving text messages in single member households, at the same time as we know individuals living alone are less likely to vote compared to individuals in multimember
households. This could potentially produce a biased treatment effect. To test if this is a concern in our study we weigh treated and non-treated subjects based on
household size using the teffects IPW command in Stata. In the model the average
treatment effect (ATE) is calculated in two stages. First, we fit a logit model with treatment as the outcome variable and household size as our predictor. Once the logit model is fitted we obtain the predicted probability of receiving a text message for each observation in the data. In the second stage, these predicted probabilities are used as weights to estimate the ATE of receiving the text message on voting.
The table shows that the ATE is almost identical to the ITT for all groups reported in Table 3 in the manuscript.
Online Appendix C: Multivariate regressions
First time Voters:
Foreign Nationals
Other first generation immigrant s
Native Norwegian s Below Age 30
Native Norwegian Age 30 and Above SMS text
message
4.27 (.48)
2.16 (.33)
3.31 (.47)
.30 (.19)
Male -5.12
(.40)
-6.48 (.33)
-6.52 (.38)
-3.28 (.14) Married 2.54
(.42)
9.37 (.35)
12.79 (.83)
15.22 (.15)
Age .84
(.12)
1.37 (.07)
-20.44 (.88)
1.59 (.03) Age-
squared
-.008 (.00)
-.012 (.00)
0.43 (0.02)
-.012 (.00) Citizenship
(Norwegian )
11.15 (.66)
2.62 (.43)
Immigrant from West
-18.12 (.42)
2.12 (.41) Time in
Norway
8.21 (.15)
0.68 (.02)
Oslo 4.74 8.40 16.18 11.57
(.41) (.34) (.49) (0.18) Constant 7.14
(2.46)
-14.94 (1.72)
282.47 (10.29)
15.77 (.90)
N 41,400 81,356 66,086 389,107
R-squared .08 .08 .04 .05
