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TruthScape Weighted Index of RuneScape Prices (TWIRP) TWIRP Weekly Reports and Economic Analyses

This quick guide explains the nuts and bolts of the TruthScape Weighted Index of RuneScape Prices (TWIRP) for those who just want to understand the basics of how it works. It provides a brief overview of the system, explains the indexes and their limitations, shows how weekly reports are laid out, and summarizes each of the TWIRP indexes.

If you want a full explanation of TWIRP, please read Understanding TWIRP and TWIRP Index Details.

Most RuneScape players are very interested in the state of the game's economy and what is happening to the prices of key items. Unfortunately, there has never been a way within the game to keep track of prices systematically, nor to be able to really tell what is going on with the economy as a whole. The goal of TWIRP is to solve this problem by selecting a set of items that represent the state of the RuneScape economy, track them over time, and use them to compute indexes that provide useful information to players.

Based on research and my own experience, I identified approximately 300 items that span the breadth of activities in the game: combat, non-combat skills, minigames and “fun” pursuits. I record the prices of each of these items every week, and feed them into a set of formulas. These produce a set of about 60 indexes and subindexes that provide an essential look at not only what prices are doing in the game, but how these changes affect players. I then publish these results in a weekly report for your perusal.

What's unique about TWIRP is that it doesn't just measure raw item cost changes. Instead, it attempts to model the behavior of RuneScape players and to analyze how item price changes affect the average player as a whole, as well as those who concentrate on particular activities.

One way that TWIRP differs from simpler methods of tracking item prices is that all TWIRP indexes are computed as weighted averages of the price changes of their underlying items. The weights are assigned to reflect the relative importance of each item to its index, based on factors such as how often the item is used, how essential players consider it to be, and how sensitive they are to changes in its price. For example, an index measuring the value of output from the Woodcutting skill would necessarily weight yew logs much higher than teak logs.

Skills and activities in RuneScape can be differentiated based on whether they mainly consume input materials, mainly produce output goods, or do both. These three main TWIRP index types reflect the different ways of representing item price trends in these cases:

• Income Indexes: These indexes measure changes in the value of output for a skill or activity. Income indexes are used for skills like Woodcutting and Mining, which don't use raw materials.
  
  
• Affordability Indexes: These indexes measure changes in how affordable the inputs are to skills and activities; higher values mean that the raw materials are getting more affordable (cheaper), improving the value of the skill. Affordability indexes are used for measuring input in skills like Prayer and Firemaking, which primarily consume goods without producing items.
  
  
• Yield Indexes: Finally, these indexes represent the profitability of a skill or activity that has both inputs and outputs, calculated from its income index and affordability index. When the income index or affordability index increase, so does the yield index; when they decrease, yield goes down.

In addition to these there are composite indexes, which are higher-level indexes computed from lower-level ones. They show a bigger picture of the economy as a whole. And finally, there are a few specialty indexes that don't fit into any of these four categories.

All indexes are recorded as weighted averages of the percentage change of item prices between their initial base value and their current value. The indexes (with one special exception) are expressed as a number that represents the relative change in that index from an initial value of 100. For example, if the value of an index is 90, that means the index has dropped by 10% since TWIRP began; if it is 110, then the index has gone up by 10%. All indexes began at 100 on December 31, 2007.

Note that all indexes only show relative price trends. The specific numbers do not have any meaning on their own; they do not say anything absolute about the skill or activity, whether it is worth doing or makes money or so forth. In the same vein, you cannot compare indexes between skills and conclude that one is “better” than the other. In most cases, each index should only be compared to its own previous values, to show trends over time.

While I believe that TWIRP gives the best overall view of the current state of the RuneScape economy, it is definitely not perfect. Please keep in mind these caveats:

• The value of the indexes depends on the accuracy of prices obtained from the Grand Exchange. Right now many listed “average” prices in the GE do not properly reflect the state of the market, and this will continue until the GE is improved.
  
  
• The indexes cannot track every item in the game, only a representative sample, which means only certain changes will be reflected.
  
  
• The weightings used for indexes are based on personal experience and research, but still required a fair bit of guesswork.
  
  
• All indexes are “backwards looking”: they describe what has happened in the past. Remember that a trend in prices can stop and even reverse itself at any time, even if it has gone on for many weeks.
  
  
• TWIRP is new and so there may be calculation problems or logic errors in my calculations that could take some time to work through.

Each week I will record the prices for all of the items used by TWIRP and then write a report to be published on TruthScape. Here is a rough outline of the typical report's structure.

The main report page for the week contains introductory information, a quick index summary and a brief commentary. The index summary shows the values of important high-level indexes, including the main index (TWIRP) that shows the overall impact of price changes on a typical RuneScape player. The synopsis contains a brief analysis of overall issues in the economy for that week.

The main report page also has links to several subordinate pages that contain more detailed indexes, charts and further analysis. These pages are as follows:

• TWIRP Composites Report and Analysis: Lists high-level (composite) index values, showing a high-level look at the state of the economy.
  
  
• TWIRP Weekly Winners and Losers: Lists the top 10 “winner” and “loser” items, based on percentage of value increase or decrease, as well as the top 5 “winner” and “loser” indexes.
  
  
• TWIRP Skills Report and Analysis: Provides detailed index information for individual skills and aggregate indexes by skill level.
  
  
• TWIRP Combat and Monster Drops Report and Analysis: Shows trends in the affordability of combat and the value of monster drops.
  
  
• TWIRP Minigames Report and Analysis: Reports on trends in item values and profitability for item-oriented minigames.
  
  
• TWIRP Special Indexes Report and Analysis: Gives details and information on special indexes not covered by the other categories.

Table 99 contains a list of all of the TWIRP indexes reported, organized by category, and each with a brief description of what the index measures or describes.

Table 99: TWIRP Index Summary Table

Index Name	Index Abbreviation	Description
Global Composite Yield	TWIRP	Main TWIRP index of the economic impact of price changes in RuneScape.
Global Composite Affordability	TWIRPa	Affordability of all items purchased by players. First of two components of the main TWIRP index.
Global Composite Income	TWIRPi	Value of all items created or earned by players. Second of two components of the main TWIRP index.
Skill Composite Yield	TWIRP-S	Overall yield (based on income and affordability) of non-combat skills.
Combat Composite Yield	TWIRP-C	Overall yield (based on income and affordability) of combat activities.
Skill Composite Yield (l)	TWIRP-S(l)	Subindex of TWIRP-S showing price change impacts for players with lower skill levels (1 to 40).
Skill Composite Yield (m)	TWIRP-S(m)	Subindex of TWIRP-S showing price change impacts for players with medium skill levels (41 to 70).
Skill Composite Yield (h)	TWIRP-S(h)	Subindex of TWIRP-S showing price change impacts for players with higher skill levels (71 to 99).
Construction Affordability	TWIRP-S-CONa	Affordability of training Construction (higher levels mean it is cheaper.)
Cooking Yield	TWIRP-S-COOKy	Yield (output net of input costs) for the Cooking skill.
Crafting Yield	TWIRP-S-CRFTy	Yield for the Crafting skill.
Farming Yield	TWIRP-S-FARMy	Yield for Farming.
Firemaking Affordability	TWIRP-S-FMa	Affordability of the Firemaking skill.
Fishing Income	TWIRP-S-FISHi	Changes in the value of Fishing income.
Fletching Yield	TWIRP-S-FLTy	Yield for Fletching.
Herblore Yield	TWIRP-S-HERBy	Yield, or profitability, for Herblore.
Hunter Income	TWIRP-S-HUNTi	Income trends for the Hunter skill.
Magic Affordability	TWIRP-S-MAGICa	Affordability of training Magic (specifically non-combat magic).
Mining Income	TWIRP-S-MNGi	Mining output value.
Prayer Affordability	TWIRP-C-PRAYa	Affordability of Prayer training. Note that this is a combat-specific skill and so is part of TWIRP-C and not TWIRP-S.
Runecrafting Yield	TWIRP-S-RCy	Profitability of the Runecrafting skill.
Slayer Yield	TWIRP-C-SLAYy	Slayer yield. Note that this is a combat-specific skill and so is part of TWIRP-C and not TWIRP-S.
Smithing Yield	TWIRP-S-SMITy	Yield trend for the Smithing skill.
Thieving Income	TWIRP-S-THVi	Thieving income trends.
Woodcutting Income	TWIRP-S-WCi	Output value from Woodcutting.
Food Affordability	TWIRP-C-FOODa	Affordability of food used for combat. Common to all combat styles.
Potion Affordability	TWIRP-C-POTa	Affordability of potions for combat. Common to all combat styles.
Miscellaneous Item Affordability	TWIRP-C-MISCa	Affordability of miscellaneous combat items. Common to all combat styles.
Melee Affordability	TWIRP-C-MELa	Overall affordability of melee combat (including equipment and supplies.)
Ranged Affordability	TWIRP-C-RNGa	Overall affordability of ranged combat (including equipment and supplies.)
Magic Affordability	TWIRP-C-MAGa	Overall affordability of mage combat (including equipment and supplies.)
Monster Drop Value (Low-Level)	TWIRP-C-DROP(l)	Drop value trends for lower-level monsters (up to level 60).
Monster Drop Value (Mid-Level)	TWIRP-C-DROP(m)	Drop value trends for mid-level monsters (levels 61 to 120).
Monster Drop Value (High-Level)	TWIRP-C-DROP(h)	Drop value trends for higher-level monsters (over 120).
Monster Drop Value (Bosses)	TWIRP-C-DROP(b)	Drop value trends for boss monsters (Kalphite Queen, Dagannoth Kings, etc.)
Monster Drop Value	TWIRP-C-DROP	Composite monster drop value created from the four level-specific drop value indexes just above.
Gem Drop Value	TWIRP-C-DROP-GEM	Drop value subindex for standard uncut gems and half keys.
Herb Drop Value	TWIRP-C-DROP-HERB	Drop value subindex for all regularly dropped herbs.
High-Level Herb Drop Value	TWIRP-C-DROP-HHERB	Drop value subindex for high level herbs (ranarr and over).
Herb Seed Drop Value	TWIRP-C-DROP-HSEED	Drop value subindex for all herb seeds.
High-Level Herb Seed Drop Value	TWIRP-C-DROP-HHSEED	Drop value subindex for high level herb seeds (ranarr and up).
Allotment Seed Drop Value	TWIRP-C-DROP-ASEED	Drop value subindex for allotment seeds.
Barrows Yield	TWIRP-M-BARy	Relative profitability trend of the Barrows combat minigame.
Impetuous Impulses Income	TWIRP-M-IMPi	Reward value for Impetuous Impulses.
Fishing Trawler Income	TWIRP-M-TRAWi	Reward value for the fishing trawler.
Kingdom of Miscellania Income	TWIRP-M-MISCi	Output value from the Kingdom of Miscellania.
Mage Training Arena Yield	TWIRP-M-MTAy	Profitability of using the Mage Training Arena.
Treasure Trails Income	TWIRP-M-TTi	Reward value from treasure trails.
Discontinued Items Affordability	TWIRP-X-DISCa	Affordability of discontinued items (“rares”).
Luxury Items Affordability	TWIRP-X-LUXa	Affordability of luxury items, including rares, expensive armor and weapons and treasure trail rewards.
Powerleveling Affordability	TWIRP-X-POWa	Affordability of using expensive items to powerlevel combat or non-combat skills.
Key Items Affordability	TWIRP-X-KEY	This is a simple index of the prices of the 50 items I feel are most important to the RuneScape economy. See TWIRP Special (Extra) Indexes for details.
High Alchemy Affordability	TWIRP-X-ALCHa	A special index that measures the affordability of training Magic by high alching, based on price changes relative to high alch values. See TWIRP Special (Extra) Indexes for details.
Crude Volatility Index	TWIRP-X-VOL	Provides a general indication of overall market volatility, meaning how much prices are changing in the aggregate. This is the only index not computed just from prices using an initial base value. See TWIRP Special (Extra) Indexes for details.

TruthScape Weighted Index of RuneScape Prices (TWIRP) TWIRP Weekly Reports and Economic Analyses

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