Similar to all other types of information, public opinion polls can influence public opinion. We present two hypotheses to understand how polls affect public opinion: the bandwagon and the underdog effect. The bandwagon effect claims that voters “jump on the bandwagon,” which means that if a party is gaining in the polls, the party will gain additional support from the voters, and vice versa if the party is losing in the polls. The underdog effect suggests that if a party is losing in the polls, the party will gain some sympathy votes to offset this loss. We use a survey experiment to test the two hypotheses. We find evidence of the bandwagon effect, and the effect is strongest in the positive direction. When voters learn that a party is gaining in the polls, voters will be more likely to vote for it. There is also some evidence for the negative bandwagon effect. We find no evidence for the underdog effect. The effects head in the same direction regardless of the size of the party. We conclude by discussing the implications of our findings with regards to a potential ban on publishing opinion polls.

Using close election outcomes, we identify a personal effect of incumbency on the probability of seeking election, and seeking and winning office in subsequent elections for elected officials in an Open List Proportional System. In many cases Danish local elections creates an as-if random distribution of candidates that are elected or not, which is an ideal setting for a Regression Discontinuity design. The incumbency advantage has been studied to a great extent, though primarily in pluralistic electoral systems, while more recent studies have extended the scope to Proportional Representation systems. This study adds to this budding literature by showing an advantage in a new context and focusing on candidate level electoral returns under conditions where candidates are arguably least likely to benefit from incumbency.

A vast amount of experimental evidence suggests that get-out-the-vote encouragements delivered through door-to-door canvassing have large effects on turnout. Most of the existing studies have been conducted in the United States, and are inspiring European mobilization campaigns. This article explores the empirical question of whether the American findings are applicable to Europe. It combines existing European studies and presents two new Danish studies to show that the pooled point estimate of the effect is substantially smaller in Europe than in the United States, and finds no effects in the two Danish experiments. The article discusses why the effects seem to be different in Europe compared to the United States, and stresses the need for further experiments in Europe as there is still considerable uncertainty regarding the European effects. While one  possible explanation is that differences in turnout rates explain the differences in effect sizes, the empirical analysis finds no strong relationship between turnout and effect sizes in either Europe or the United States.

Despite the widespread scholarly attention given to get-out-the-vote tactics the
recent one and a half decade, few have studied the effect of short text
messages (SMS) on voter turnout, and no previous such study has been
conducted outside the US. We analyze four SMS experiments with more than
300,000 voters conducted in relation to two elections in Denmark and find
intention-to-treat (ITT) effects between 0.33 and 1.82 percentage points with a
pooled effect of 0.74 percentage points. Furthermore, we vary the timing and
the content of the messages to test existing theories of text messages as
mobilization tools. In one experiment, we find messages delivered before
Election Day to have a higher effect than those delivered on Election Day, while
we find no additional effect of delivering multiple messages. We also vary
message content and in general find no significant differences from sending
different messages.

Scholars have argued that becoming a parent impacts political behavior, includ-ing turnout. In this paper, we identify the effect on turnout of having an additionalchild conditional on the decision to become a parent. When parents have a child,nature sometimes assigns additional children through twinning. We argue thatconditional on age of parents and birth cohort this as-if randomly assigns an extrachild to some parents. With a large dataset of family composition and validatedturnout for Danish voters, we find, consistent with additional children taking upparents’ time and indirectly increasing the cost of voting, that having an additionalchild at the same time as another depresses turnout for both parents. Mothers’who had twins in their first parity are 1.6 to 3.0 percentage points less likely tovote across three elections. For fathers, turnout is only depressed by 0.7 to 1.4percentage points.

Scholars have argued that children affect their parents’ political behavior, including turnout, through so-called trickle-up socialization. However, there is only limited causal evidence for this claim. Using a regression discontinuity design on a rich dataset, with validated turnout from subsets of Danish municipalities in four elections, we causally identify the effect of parenting a recently enfranchised voter. We consistently find that parents are more likely to vote when their child enters the electorate. On average across all four elections, we estimate that parents become 2.8 percentage points more likely to vote. In a context where the average turnout rate for parents is around 75%, this is a considerable effect. The effect is driven by parents whose children still live with them while there is no discernible effect for parents whose child has left home. The results are robust to a range of alternative specifications and placebo tests.