It depends on what you are actually after, e.g. below are two orders, but there are two transaction type in different weekdays, both sub total will be involved in the calculation of avg for that weekday separately. While in order wise, the subtotal for the order should be 0 no matter which weekdays it is. So not sure which is your expected logic to calculate the average for this case.
Thanks for taking the time to take a look at this.
You are correct any orders below zero is a refund so it shouldnt be considered in the averages.
What Im trying to get is the averages per day per weekday.