It’s amazing how quickly some analysts jump to conclusions without any facts to break their fall. Discussions of Dean Heller’s potential appointment to John Ensign’s (R) Senate seat provide the latest example of fact-free commentary.

Talk about the “incumbent advantage” Rep. Heller (R) will gain by virtue of this appointment ignores the historical record, which makes clear that appointed incumbents gain no advantage. Telling titles of two academic treatises summarize the facts: “Treadmill to Oblivion: The Fate of Appointed Senators” and “The Electoral (Mis) Fortunes of Appointed Senators and the Source of Incumbency Advantage.”

Since popular election of senators began in 1913, 118 appointed senators sought election and just 62 – or 52.5 percent – won their seats. Nate Silver of Fivethirtyeight.com confines his analysis to Senate appointments since 1956 and finds that 51 percent won election.

An appointed senator has about the same odds of winning a coin flip as (s)he does of keeping his or her seat: about the same odds as an otherwise evenly matched race for an open seat.

By striking contrast, depending on exactly how one makes the calculation, 84 to 88 percent of Senate incumbents are reelected.

Scholars offer several explanations for the failure of appointed senators to inherit the advantages of incumbency.

First, they tend to attract higher-quality challengers. About three-quarters of appointed incumbents faced members of Congress or top-of-the ticket statewide elected officials. Only a third of their elected colleagues stood against opponents with that caliber of political experience. Challengers to appointed senators also raise about a third more money than those taking on elected incumbents.

Second, it would appear that part of senators’ incumbency advantage arises from the very process of getting elected. While House members can provide services to, and communicate directly with, a meaningful portion of their constituency over two years, senators directly affect a lesser proportion of their larger constituencies over an equivalent period of time.

However, during the campaigns they wage, victorious senators spend substantial time and energy meeting constituents, and significant dollars defining themselves for voters. Moreover, in the end, voters see the efforts of elected incumbents validated by their friends, neighbors and fellow citizens, most of whom, by definition, support the winner.

Appointed incumbents have waged no previous campaign, and their tenure is neither validated nor legitimized by the citizenry.

Legitimacy provides another explanation for the failure of appointed senators: Voters prefer elections to appointments. For many, democracy is defined by elections. That’s why, by 3 to 1, voters prefer to see state Supreme Court justices elected rather than appointed. Voters resent a single individual stuffing a U.S. senator down their throats in a process that appears questionable. After all, how many other vacancies in the ranks of elected officials are filled by appointment? Most prominently, House vacancies require an election. Is the Senate a lesser office?

Indeed, the 17th Amendment, which provides for popular election of senators, makes clear that elections are the proper way to fill a vacancy: “When vacancies happen