This question investigates the likelihood that groups were allocated in a random manner using accepted techniques. Issues with the approach to randomization can occur when accepted methods are not used to allocate subjects to study groups, such as date of birth, date/order of presentation, or convenience sampling.
Were there any issues with the randomization methods used to assign subjects to groups that could have led to meaningful differences between the groups at the time of enrollment?
Was the allocation sequence assigning each subject to a group fully random?
Example of random sequence generation: We generated the two comparison groups using simple randomization, with an equal allocation ratio, by referring to a table of random numbers.
Example of non-random sequence generation: Those born on even dates were resuscitated with room air (room air group), and those born on odd dates were resuscitated with 100% oxygen (oxygen group).