chain base index numbers

• Compares prices from each year with that of the previous year
• Show how values change from year to year
• The previous year is used as the base year – this means the base year will change every time
• 𝑪𝒉𝒂𝒊𝒏 𝑩𝒂��𝒆 𝑰𝒏𝒅𝒆𝒙 𝑵𝒖𝒎𝒃𝒆𝒓𝒔 = 𝒑𝒓𝒊𝒄𝒆 /𝒍𝒂𝒔𝒕 𝒚𝒆𝒂𝒓 ′𝒔 𝒑𝒓𝒊𝒄𝒆 × 𝟏𝟎0
• RPI and CPI are chain base index numbers and show how values change monthly or annually. CPI is published monthly by ONS