Weeks without purchases count too: average the whole period
By Erik Nilsen · Kroni2 min read
An average per week must include every week in the period, including weeks when your child bought nothing. Counting only shopping weeks produces another average. Both can be calculated, but they need different labels.
Four weeks, two containing payments
In a hypothetical example, optional spending is 10 units in week one, zero in week two, 20 in week three and zero in week four. The arbitrary amounts are invented and the period contains exactly four weeks.
Total spending is 10 + 0 + 20 + 0 = 30 units. The average per calendar week is 30 / 4 = 7.50. The average for only the two weeks containing purchases is 30 / 2 = 15.
Fifteen is valid as an average per shopping week. However, 15 × 4 = 60 does not describe spending during the four actual weeks, which was 30. It mixes a rate per shopping week with a calendar-week count.
Write the zero weeks explicitly
A practical snag is empty weeks disappearing from the sheet and your child dividing by the visible row count. Write one row per week and zero when no purchases occurred. The period's length becomes clear.
The average of 7.50 summarises spending rather than representing a payment each week. Retain the actual 10 and 20 rather than entering four invented expenses of 7.50.
If your family uses this history for a new plan, examine whether coming weeks are comparable. A planned larger item can make the old average unhelpful. Neither calculation promises future spending.
Ask your family: “Do we mean per week across the whole period or only per week when something was purchased?”
Clarify what the virtual balance represents
Kroni keeps track using a virtual balance and does not transfer money. Cash your child has received and amounts an adult still owes are different things. This exercise concerns money actually received. Agree how it fits your record so the same amount is not counted both as received and still unpaid. Read about allowance in Kroni.
