## FANDOM

44,133 Pages

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

## 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:

Icon Item Price Direction Low Alch High Alch Limit Members Details Last updated
Achey tree logs989
1225,000view55 days ago
Arctic pine logs324
142125,000view55 days ago
Elder logs8,835
19228825,000view55 days ago
Logs291
1225,000view55 days ago
Magic logs380
12819225,000view55 days ago
Mahogany logs300
203025,000view55 days ago
Maple logs108
324825,000view55 days ago
Oak logs591
81225,000view55 days ago
Teak logs105
121825,000view55 days ago
Willow logs248
162425,000view58 days ago
Yew logs167
649625,000view58 days ago

8 November 2013
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

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}
Community content is available under CC-BY-SA unless otherwise noted.