Which of the following is a major type of medication error?

The selection of incorrect dosage administration as a major type of medication error is important because it directly affects patient safety and treatment efficacy. Administering the wrong dosage can lead to under-treatment or overdose, significantly impacting a patient's health. For example, an incorrect dosage can cause adverse drug reactions or therapeutic failures, making it essential for pharmacy technicians to pay close attention to the dosage prescribed and ensure it is given as intended.

Other options, while they may represent issues within pharmacy operations, do not have the same direct and immediate impact on patient health as incorrect dosage administration. Incorrect prescription format is more of a procedural issue rather than one that would directly harm a patient if caught before dispensing. Missed pharmacy hours, although inconvenient, do not pose a direct risk to a patient’s wellbeing. Similarly, consolidated billing errors relate to billing and insurance processes rather than the administration of medication itself.