RuneScape:Grand Exchange Market Watch/Log Index

The Log Index is made up of a weighted average of all of the current logs listed in the Market Watch, with the starting date of this average on 19 December 2007, at an index of 100. The overall rising and falling of log prices is reflected in this index.

While specialised for just watching log prices, it is set up and adjusted in a manner similar to the Common Trade Index, and the divisor may be adjusted to include new logs added by Jagex (see the FAQ for more information).

As of today, this index is 829.87  +4.95

Historical chart

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Summary

Any suggested changes to this index should be added to the talk page.

• Start date: 19 December 2007 (at index of 100)
• Index today: 829.87
• Change today:  +4.95
• Number of items: 11 (last adjusted on 8 November 2013)
• Index divisor: 10.3117 (last adjusted on 8 November 2013)

List of items

This is the current list of items included in this index:

Adjustments

Icon	Item	Price	Direction	Low Alch	High Alch	Limit	Members	Details	Last updated
	Elder logs	8,835		192	288	25,000		view	4 years ago
	Magic logs	380		128	192	25,000		view	4 years ago
	Yew logs	167		64	96	25,000		view	4 years ago
	Arctic pine logs	324		14	21	25,000		view	4 years ago
	Logs	291		1	2	25,000		view	4 years ago
	Maple logs	108		32	48	25,000		view	4 years ago
	Mahogany logs	300		20	30	25,000		view	4 years ago
	Oak logs	591		8	12	25,000		view	4 years ago
	Teak logs	105		12	18	25,000		view	4 years ago
	Achey tree logs	989		1	2	25,000		view	4 years ago
	Willow logs	248		16	24	25,000		view	4 years ago

8 November 2013

Adjusted index: Log Index Adjustment date: 8 November 2013 Affected templates: Template:GE Log Index and Template:GE Log Index/Diff Added item(s): Elder logs Removed item(s): None Items before adjustment: 10 Items after adjustment: 11 Divisor before adjustment: 10.0000 Divisor after adjustment: 10.3117 Item Base date Base price Price on adjustment date Comments Logs 19 December 2007 34 28 Unchanged Achey tree logs 40 39 Oak logs 18 12 Willow logs 22 20 Teak logs 136 71 Maple logs 46 30 Mahogany logs 173 392 Arctic pine logs 855 57 Yew logs 413 526 Magic logs 1,221 1,646 Elder logs – – 3,952 Added item Calculations From the old divisor obtained from the templates: ${div}_{\text{old}} = 10.0000$ We need to calculate a new divisor: ${div}_{\text{new}} = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}}$ To calculate the new divisor, we need to find: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{old}} & = \text{sum of ratios prior to change} \\ & = \frac{280}{34} + \frac{399}{40} + \frac{123}{18} + \dots + \frac{1,646}{1,221} \\ & = 32.08119681 \text{ (up to 8 d.p.)} \end{align}$ And also: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{new}} & = \text{sum of ratios prior to change} - \text{sum of removed ratios} + \text{sum of added ratios} \\ & = \sum \left ( \frac{p}{q} \right )_{\text{old}} - \text{sum of removed ratios} + \text{number of added items} \\ & = 32.08119681 - 0 + 1 \\ & = 33.08119681 \text{ (up to 8 d.p.)} \end{align}$ Thus, the new divisor is: $\begin{align} {div}_{\text{new}} & = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}} \\ & = 10.0000 \times \frac{33.08119681}{32.08119681} \\ & = 10.3117 \text{ (4 d.p.)} \end{align}$