RuneScape:Grand Exchange Market Watch/Food Index

The Food Index is made up of a weighted average of all of the current foods listed in the Market Watch, with the starting date of this average on 12 January 2008, at an index of 100. The overall rising and falling of food prices is reflected in this index.

While specialised for just watching food 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 food added by Jagex (see the FAQ for more information).

As of today, this index is 455.18  -1.34

Historical chart

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Summary

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

• Start date: 12 January 2008 (at index of 100)
• Index today: 455.18
• Change today:  -1.34
• Number of items: 19 (last adjusted on 12 January 2008)
• Index divisor: 19.0000 (last adjusted on 12 January 2008)

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
	Bass	299		108	162	10,000		view	4 years ago
	Bread	323		9	14	1,000		view	4 years ago
	Cake	579		20	30	1,000		view	4 years ago
	Cavefish	2,540		140	210	10,000		view	4 years ago
	Chocolate cake	890		28	42	1,000		view	4 years ago
	Great white shark	2,377		130	195	10,000		view	4 years ago
	Lobster	141		107	160	10,000		view	4 years ago
	Monkfish	388		92	138	10,000		view	4 years ago
	Rocktail	4,690		240	360	10,000		view	4 years ago
	Salmon	29		35	52	10,000		view	4 years ago
	Saradomin brew (4)	19,880		80	120	1,000		view	4 years ago
	Shark	1,933		120	180	10,000		view	4 years ago
	Swordfish	157		160	240	10,000		view	4 years ago
	Tuna	37		48	72	10,000		view	4 years ago
	Strawberries (5)	1,423		0	0	10,000		view	4 years ago

20 May 2015

Adjusted index: Food Index Adjustment date: 20 May 2015 Affected templates: Template:GE Food Index and Template:GE Food Index/Diff Added item(s): 7 — Bread, Cavefish, Great white shark, Rocktail, Salmon, Saradomin brew (4), Strawberries (5) Removed item(s): 11 — Admiral pie, Garden pie, Kebab, Manta ray, Redberry pie, Roast bird meat, Sea turtle, Stew, Sweetcorn, Ugthanki kebab, Wild pie Items before adjustment: 19 Items after adjustment: 15 Divisor before adjustment: 19.0000 Divisor after adjustment: 8.7619 Item Base date Base price Price on adjustment date Comments Lobster 25 January 2008 175 196 Unchanged Bass 195 225 Tuna 81 163 Swordfish 272 295 Monkfish 233 336 Shark 657 739 Cake 52 91 Chocolate cake 150 421 Ugthanki kebab 887 810 Removed item Kebab 32 276 Sea turtle 1,264 2,690 Manta ray 1,794 1,907 Sweetcorn 135 43 Roast bird meat 22 19 Admiral pie 1,031 497 Wild pie 3,491 985 Redberry pie 381 1,280 Garden pie 657 475 Stew 100 1,102 Bread – – 433 Added item Strawberries (5) 318 Saradomin brew (4) 9,762 Salmon 80 Cavefish 1,256 Rocktail 1,814 Great white shark 912 Calculations From the old divisor obtained from the templates: ${div}_{\text{old}} = 19.0000$ 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: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{old}} & = \text{sum of ratios prior to change} \\ & = \text{sum of unchanged ratios} + \text{sum of removed ratios} \\ & = \left (\frac{196}{175} + \frac{225}{195} + \dots + \frac{421}{150} \right ) + \left (\frac{810}{887} + \frac{276}{32} + \dots + \frac{1,102}{100} \right ) \\ & = 42.27255853 \text{ (up to 8 d.p.)} \end{align}$ And also: $\begin{align} \sum \left ( \frac{p}{q} \right )_{\text{new}} & = \text{sum of ratios prior to change} - \text{sum of removed ratios} + \text{sum of added ratios} \\ & = \sum \left ( \frac{p}{q} \right )_{\text{old}} - \text{sum of removed ratios} + \text{number of added items} \\ & = 42.27255853 - \left ( \frac{810}{887} + \frac{276}{32} + \dots + \frac{1,102}{100} \right ) + 7 \\ & = 19.49428715 \text{ (up to 8 d.p.)} \end{align}$ Thus, the new divisor is: $\begin{align} {div}_{\text{new}} & = {div}_{\text{old}} \times \frac{\sum \left ( \frac{p}{q} \right )_{\text{new}}}{\sum \left ( \frac{p}{q} \right )_{\text{old}}} \\ & = 19.0000 \times \frac{42.27255853}{19.49428715} \\ & = 8.7619 \text{ (4 d.p.)} \end{align}$