There is one necessary condition for the selection of a vice president, and that is whether the individual has the experience and capacity to become president of the United States on Day One. Nine vice presidents have succeeded to the presidency upon vacancy of that office — one in five presidents. Five of those nine vice presidents became president after fewer than 200 days as vice president, and on average they served less than one year (357 days) before moving higher.

Good luck and excellent surgeons at George Washington University saved the life of Ronald Reagan only 69 days into the vice presidency of George H.W. Bush. A failed assassination attempt in 1933 on then President-elect Franklin Roosevelt prevented Vice President-elect John Nance Garner from taking office without ever serving a single day as vice president. Clearly, it is foolhardy to look at this position as one allowing for on-the-job training.

Unfortunately, too often the vice presidency has been offered for reasons of geographic or ideological balance to people who would never have been considered as viable presidential candidates in their own right. The first two transitions were to vice presidents who assumed office very early in their terms, only to follow programs diametrically opposed to their elected predecessors such that both were denied renomination in their own right.

The fatuousness of a "balanced ticket" was demonstrated in 1881 when, only six months into his term, James Garfield — a member of the so-called Half-Breed faction of the Republican Party — was replaced in office by Chester A. Arthur, a member of the so-called Stalwart faction, with the assassin shouting this desired change in the controlling faction as his motive after firing the shots.

In the field of engineering, the selection of a replacement component that was opposite of the features of the original would be viewed as flawed. If our marathon two-year campaign has any value as a vetting process, the logic would be undermined by the selection of the person who has very high odds of ascending to the presidency through a selection process that is cursory, brief and hidden and with a candidate who is at odds with the presidential candidate whose program the voters are presumably choosing for the next four years. (One indication of the inadequacy of the vice-presidential selection process is the fact that vice presidents who have succeeded to the presidency rather than being first elected in their own right scored 18 percent lower than the other presidents on historians' surveys of successful presidencies.)

A logical starting point for determining whether someone is suited to be president would be to compare his or her experience with the type of experience possessed by past presidents, especially successful ones. With that in mind, I took an average of the results of the last three major surveys by presidential historians: by the United States Presidency Centre at the University of London (2011), Siena (College) Research Institute (2010), andC-SPAN(2009). Eighty percent of the presidents in the top quartile in those surveys had prior experience in each of the following: foreign policy/national security, prior experience inWashington, D.C.and experience as a legislator.

In taking the top half of presidential performers, 80 percent had prior D.C. experience, 75 percent had prior experience as legislators and 70 percent had prior foreign policy/national security experience. In comparing the average survey rankings of presidents with various types of experience with those lacking such experience, the top three performers were presidents with prior foreign policy/national security experience (ranking 39 percent higher), prior federal executive experience (18 percent higher) and prior experience as governor (16 percent higher). The three worst categories of performance were the few presidents with prior experience as mayors (rank 43 percent lower), generals (27 percent lower) and businessmen (20 percent lower).

Putting it all together, I developed a formula based on average years of experience compared with years of experience in the following areas, in declining order of importance: total years of relevant career experience; foreign/national security policy; experience in Washington, D.C.; experience as a legislator at both state and national levels; and experience as governor.

The results of the formula are intended as just one criterion to provide some standard of minimal qualification for office, given the brief and secretive way vice-presidential candidates are selected. Using this approach, the major recent vice presidential candidates would have scored as follows: Joe Biden, 86.2 percent; Joe Lieberman, 86.2 percent; Dick Cheney, 83.5 percent; John Edwards, 52.3 percent; and Sarah Palin, 22.3 percent.

Nine of the leading possibilities reportedly under consideration by Mitt Romney would score as follows: Rob Portman, 68.7 percent; Tim Pawlenty, 61.8 percent; Robert McDonnell, 61.2 percent; John Thune, 56.6 percent; Bobby Jindal, 56.3 percent; Paul Ryan, 54.7 percent; Marco Rubio, 48.1 percent; Kelly Ayotte, 28.6 percent; and Chris Christie, 16.8 percent.

Given the presumptive Republican nominee's own lack of experience in foreign policy, national security policy, as a legislator and in working the hallways of Washington, he would do well to find a candidate with whom he is philosophically compatible who also brings experience across these areas associated with past success.

David Wise is a businessman and writer who lives in Annapolis. A three-time delegate to the Democratic National Convention, he is now a political independent. His email is wisedw@comcast.net.