Editing Price index (section)

==== Lowe index ====
Named after [[Joseph Lowe (economist)|Joseph Lowe]], this uses fixed quantity weights from an expenditure base period (<math>b</math>), typically earlier than both the base (<math>t_0</math>) and current (<math>t_n</math>) periods, where the principal modification is to draw quantity weights less frequently than every period:<ref name="hill23">Peter Hill. 2010. "Lowe Indices", chapter 9, pp. 197–216 in W.E. Diewert et al., ''[http://www.indexmeasures.ca/Vol6_10,09,26.pdf Price and Productivity Measurement: Volume 6]''. Trafford Press</ref>

: <math>P_{Lo} = \frac{\sum p_{c,t_n} q_{c,b}}{\sum p_{c,t_0} q_{c,b}}</math>

Unlike Laspeyres or Paasche, which draw weights from indexed periods, Lowe indices inherit weights from surveys (e.g., household budgets), often conducted every few years, while prices are tracked each period.<ref>https://www.bls.gov/pir/journal/gj14.pdf, citing International Labour Office (2004) paragraphs 1.17-1.23</ref> For a consumer price index, these weights on various expenditures are typically derived from household budget surveys, which occur less often than price data collection.<ref name="hill23" /> Used in most CPIs (e.g., [[Statistics Canada]], [[U.S. Bureau of Labor Statistics]]), it’s a "modified Laspeyres" where Laspeyres and Paasche are special cases if weights update every period.<ref>{{Cite web |date=19 December 2014 |title=Consumer Price Index |url=http://www.statcan.gc.ca/pub/62-553-x/2014001/chap/chap-6-eng.htm}}</ref><ref>{{Cite web |title=Different ways of measuring the Consumer Price Index (CPI) |url=http://www.statisticalconsultants.co.nz/blog/different-ways-of-measuring-the-cpi.html}}</ref><ref>[http://www.imf.org/external/pubs/ft/wp/2012/wp12105.pdf Post-Laspeyres], IMF WP/12/105</ref><ref>Bert M. Balk, [https://www.jstor.org/stable/23813500 Lowe and Cobb-Douglas], Jahrbücher für Nationalökonomie und Statistik, 230:6, 726–740</ref> The [[Geary–Khamis dollar|Geary-Khamis method]], used in the [[World Bank]]’s [[International Comparison Program]], fixes prices (e.g., group averages) while updating quantities.<ref name="hill23" />