A time series has values for 7 years. How many 3-year moving averages can be worked out from it?

Explanation

1. 01

   The groups are years 1–3, 2–4, 3–5, 4–6 and 5–7.

2. 02

   That is $7 - 3 + 1 = 5$ moving averages; the first and last years get none.