The prolonged absence of Kim Jong-un and the surprise arrival of a high powered North Korean delegation for the closing ceremony of the Asia Games in South Korea have re-energised the tired old practice of North Korean leadership speculation. Much of the coverage has followed a familiar pattern: theory and rumour based on limited evidence or unidentified sources.

Unsurprisingly, this means there is much less to the two most prominent theories than meets the eye.

1. Imagining a coup

Among the most histrionic claims to emerge, based on statements by unnamed North Korean officials turned defectors, is that Kim Jong-un has been overthrown in a coup. Defectors are often useful sources of information, but objective observers must be wary of their biases. Defectors rejected the North Korean system and are motivated by a desire to see its overthrow. So in talking about a coup, they are perhaps describing what they want rather than what is.

As uncomfortable as it is to admit, much of the ruling class remains in North Korea for a reason: the status quo ensures their preservation, as well as stability, power and wealth. How the elite feel privately about Kim Jong-un is irrelevant; so long as he remains central to the maintenance of order, they will not have a motive to threaten him.

2. In sickness and in health

The most plausible explanation for Kim Jong-un's absence is health problems. However, though there are factors that point to a simple explanation, this hasn't stopped the spread of obscure rumours and theories, such as an allergic reaction to Swiss cheese.

A relatively fair assessment about his health can be made based on plain observation. Kim Jong-un is overweight and a smoker. But perhaps the most recent evidence that suggests health problems was the 20th anniversary of Kim Il-Sung's death in July, where one can see Kim Jong-un limping on and off stage. Based on these facts, we can posit that Kim Jong-un is likely convalescing due to a leg injury, which may have been caused or complicated by a poor lifestyle.

This episode again reminds us of how little the world knows about North Korea. Unfortunately, this has encouraged many to use the lurid and comical to find meaning, reinforcing a buffoonish perception of the country. But North Korea is a deadly serious business, and poses real problems to both regional and international security. Policy on North Korea has to be based on sound judgment of the limited available information. Speculation based on bias, rumour or media sensationalism is not helpful.