As an [Undetermined] method of dying is very similar to how people kill themselves it is probably the source of underreported suicide.

While the 1:1 ratio in the UK for the 15-24 age bracket is interesting, the study is based upon a flawed principle: undetermined death is not equivalent to suicide.

A modern coroner has two chief duties: report the manner of death (there are only 4: natural, accidental, suicide, or homicide) and the cause of death (the actual physical process involved). If the manner of death is no more compelling than one or more competing manners of death after all available information has been considered, the coroner will rule undetermined. This happens more frequently than television programs about forensic pathology have led the public to believe.

Suicide and homicide require proof beyond a reasonable doubt. There are two main criteria for determining suicide:

1. Evidence of a self-inflicted death

Any of the following may be used for this determination: pathology, toxicology, psychological evidence, statements from the decedent or witnesses.

1. Evidence of competency at the time of death with an intent to kill self

   1. Explicit verbal or nonverbal expression of intent to kill self
   2. Implicit or indirect evidence of intent to die, including the following:

   * Expression of hopelessness
   
   * Effort to procure or learn about means of death or rehearse fatal behavior
   
   * Preparations for death, inappropriate to or unexpected in the context of the decedent's life
   
   * Expression of farewell or desire to die, or acknowledgment of impending death
   
   * Precautions to avoid rescue
   
   * Evidence that decedent recognized high potential lethality of means of death
   
   * Previous suicide attempt
   
   * Previous suicide threat
   
   * Stressful events or significant losses (actual or threatened)
   
   * Serious depression or mental disorder
   

Unfortunately, this abstract does poor job of reporting the data from the study. How many Western countries were looked at? Did the ratios scale with age and gender?