RuneScape:Grand Exchange Market Watch/Adjustments (12 February 2012)

12 February 2012

Adjusted index: Common Trade Index Adjustment date: 12 February 2012 Affected templates: Template:GE Common Trade Index and Template:GE Common Trade Index/Diff Added item(s): 10 — Abyssal whip, Dragon boots, Rune armour set (lg), Red chinchompa, Oak plank, Shark, Green dragonhide, Dragon bones, Cannonball, Dragonfire shield Removed item(s): 6 — Mithril ore, Law rune, Big bones, Raw swordfish, Vial of water, Clean ranarr Items before adjustment: 23 Items after adjustment: 27 Divisor before adjustment: 21.791759207424 Divisor after adjustment: 23.9535 Item Base date Base price Price on adjustment date Comments Coal ca. December 2007 159 320 Unchanged Steel bar 540 1,335 Gold ore 528 304 Nature rune 271 226 Death rune 299 452 Pure essence 80 125 Yew logs 411 522 Magic logs 1,222 1,592 Cowhide 109 513 Flax 70 72 Soft clay 207 541 Limpwurt root 646 2,060 Raw lobster 237 285 Raw monkfish 10 January 2008 350 601 Snape grass 428 314 Clean snapdragon 6,885 9,866 Clean kwuarm 3,030 1,828 Law rune ca. December 2007 303 363 Removed item Big bones 419 621 Raw swordfish 10 January 2008 325 492 Mithril ore 315 349 Vial of water 98 36 Clean ranarr 5,959 4,958 Abyssal whip – – 420,951 Added item Dragon boots 103,701 Rune armour set (lg) 136,531 Red chinchompa 1,592 Oak plank 639 Shark 1,715 Green dragonhide 2,196 Dragon bones 3,962 Cannonball 407 Dragonfire shield 7,946,801 Calculations From the old divisor obtained from the templates: ${div}_{\text{old}} = 21.791759207424$ 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: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{old}} & = \text{sum of ratios prior to change} \\ & = \left (\frac{320}{159} + \frac{1,335}{540} + \dots + \frac{1,828}{3,030} \right ) + \left (\frac{363}{303} + \frac{621}{419} + \dots + \frac{4,958}{5,959} \right ) \\ & = 35.26980062 \text{ (up to 8 d.p.)} \end{align}$ And also: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{new}} & = \text{sum of ratios prior to change} - \text{sum of removed ratios} + \text{sum of added ratios} \\ & = \sum \left ( \frac{p}{q} \right )_{\text{old}} - \text{sum of removed ratios} + \text{number of added items} \\ & = 35.26980062 - \left ( \frac{363}{303} + \frac{621}{419} + \dots + \frac{4,958}{5,959} \right ) + 10 \\ & = 38.76853218 \text{ (up to 8 d.p.)} \end{align}$ Thus, the new divisor is: $\begin{align} {div}_{\text{new}} & = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}} \\ & = 21.791759207424 \times \frac{38.76853218}{35.26980062} \\ & = 23.9535 \text{ (4 d.p.)} \end{align}$