Missed appointments cost the NHS an estimated £600m per year. Analysis of hospital data shows that missed appointments are most common on Monday and least common on Friday. This is true for male and female patients.
The weekday effect is present in all age bands, but is strongest in young adults.
*Taken from Ellis, D. A. & Jenkins R. (2012). Weekday affects attendance rate for medical appointments: Large-scale data analysis and implications. http://dx.plos.org/10.1371/journal.pone.0051365