Where do you get the data?
Goatleg combines data from multiple places – Bricklink, LEGO.com, Brickset and Rebrickable are the main sources. These sites have APIs, download files and other public data about LEGO parts. Goatleg brings them together in a way that none of them do alone to provide a richer picture of the secondary LEGO parts market. All data is collected and used according to the terms of the source sites.
What parts are included?
Data is for individual parts, not sets or complete minifigures, although separate minifigure parts and accessories are included. The list of parts used is based on set inventory data from Rebrickable. The Rebrickable database is large (over 20,000 inventories), but not complete, so there may be some older parts that are not included in the data. Modulex and Minitalia parts are not included. Other themes like DUPLO, Bionicle, Galidor, Fabuland, Scala, Belleville and Znap are generally included in overall metrics, but may be excluded from others (as noted).
How do you calculate …X?
Here are the methods used for some of the metrics here:
Average sale price – The average sale price is the 6-month quantity average price from the Bricklink price guide on the date of the update. Quantity average prices are calculated by dividing the total value of sales by the number of parts sold.
Sell-through rate – This is a percentage calculated by dividing the quantity of parts sold in the previous six months by the sum of the parts sold plus the parts in inventory at the end of the six months. For example, if 16 parts sold during the 6-month period, and at the end of the period there were 84 parts in stock, the calculation would be 16 / (16 + 84) = 0.16, or a sell through rate of 16%.
Percent sold by value and percent sold by quantity – These numbers represent the market segments for new and used parts. Percent sold by value is the proportion of new and used parts based on the total sales value in US dollars. For example, if there are $3,000 in used parts sales and $7,000 in new part sales, the percent sold by volume is 30% used and 70% new. Percent sold by quantity is the proportion based on the total number of parts sold. For example, if 2,500 used parts are sold and 7,500 new parts are sold, the percent sold by quantity is 25% for used and 75% for new.
Average parts per lot – The total 6-month quantity of parts divided by the number of lots.
Used sold price per gram – The quantity average price divided by the weight of the part, in grams. The sums of these metrics are used for aggregated averages. As used parts are often purchased by weight, this data is given to estimate the potential margin for parts.
But you didn’t consider …
This data is not being presented to make any argument or prove any point. These are just the numbers, and efforts will always be made to be clear what is being measured and how. There are many things that are not measured by this data. An infinite number of things. If you have an interesting question the data might answer, let me know.