*Note: In the process of writing this post, I realised that to get it done properly on decent sized datasets I was going to have to write some data scraping scripts. Since I've never done that before and it might take a while to figure it out, I decided to post what I'd already done anyway. Consider it a proof of concept for now.*

In part one of this series, I took a look at the claims that all sets come with instructions these days, and that there are no basic brick boxes and buckets any more. Since these were extremely easy to disprove, I also looked at the historical trends to see if there are more sets with instructions and less basic brick boxes than there used to be.

In this part, I'll look at the claim that sets these days are filled with specialised pieces that can only be used for one thing. New Elementary has already shown that anyone claiming 'it was all basic bricks in my day' is entirely wrong, but is there any truth to the idea that today's sets have more specialised pieces than those of yesteryear?

For most Lego builders, the phrase 'specialised piece that can only be used for one thing' is likely to be taken as a challenge to find a way to use that piece for something else, hopefully resulting in massed cries of "NPU!". So the definition of a specialised piece is very subjective. If we want to objectively look at whether specialised pieces are more commonplace these days, we need some numerical definition of a specialised piece.

The best I can think of is how many sets a piece appears in. According to Bricklink, the iconic 2x4 brick, surely the least specialised of all pieces, has appeared in 1923 sets, whereas the highly specialised printed tow truck windscreen piece below has only ever appeared in one set. It's not a perfect measure by any means, but it might do for our purposes.

Nice colours though. |

The question now is what number of sets should a piece have to appear in before it's proven itself non-specialised? More than 10? Let's run the numbers. Since I mentioned tow trucks at the end of the last post, we'll look at 16 tow trucks TLG has produced over the years, and count the proportion of pieces that have appeared in fewer than 10 other sets*. Since these sets are mostly quite small (average 73 pieces) and to ensure a spread of different model types, I'll also look at 19 mid-size spaceships (average 200 pieces) and 12 train stations (average 360 pieces) as well:

What does this tell us? Well, firstly, pieces that appear in fewer than 10 other sets are really quite rare - almost always less than 5% of a set's parts. There are some higher proportions among the tow trucks and this is partly because they tend to be small sets, where just a few specialised parts will constitute a sizeable percentage of the total. Those who know a little bit about the history of Lego probably won't be surprised that the truck with 28% specialised parts was from the early 2000's, a time when the number of parts and colours spiralled out of control, with many 'juniorised' sets, containing large specialised pieces. You'll notice that this is the set that contains the unique windscreen pictured above.

Yuck. They deserved to almost go bankrupt just for inflicting this abomination upon the world. |

Those with their thinking caps on may have noticed a possible flaw in my definition. Take a specialised part that can only be used in one way, say, a tow truck's winch. Then we say that a non-specialised piece will have been used in more than 10 sets. But there have been 16 tow trucks! So if every tow truck used the same winch piece, it would have been used in 16 sets, despite only being used in one very specific way. So clearly we need a higher threshold. Probably much higher. There have been 16 tow trucks, but scores of spaceships, and we don't want a specialised spaceship piece to slip through the net if it's never been used for anything else.

So let's up the ante and define a specialised part as one that's appeared in fewer than 100 other sets:

- "Sets these days are all/mostly specialist parts" - in fact the vast majority of sets are (and always have been) less than 30% specialist parts, and the only set that can be described as mostly specialist parts is that abomination of a tow truck from 2003.
- "Ok, but they definitely include more specialist parts than they used to" - nope, and possibly the opposite, though I'd want more data to be sure of that.

Of course, if you quit Lego in disgust in the early 2000's and haven't checked out any sets since you may be partially justified in holding these opinions. It's interesting that there's a definite rise in specialised parts visible for the train stations in the early 2000's, but whether that's indicative of the known trend or just a coincidence is impossible to say given the small sample size.

Is this data representative of all sets? I don't know. The only way to tell is to repeat it for other similar sets of sets. I chose tow trucks and stations because they were some of the earliest models available and they keep being regularly made throughout the decades (spaceships didn't appear until a bit later, but have been regularly made since). I'm doing the data collection manually (indeed, literally on the back of an envelope), so I want to settle on a definition of specialised parts that I'm happy with before making efforts to analyse more sets.

Let's try a different approach. Instead of trying to define a specialised part, let's make a really strict definition of a non-specialised part - the sort of definition the oldest, grumpiest, most die-hard "Lego is rubbish these days" critic might use. Non-specialised pieces are those from these Bricklink categories:

No stupid 'modified' bricks or plates, no pretty round bricks, none of your newfangled slopes for making nice roofs, and no tiles for fussily hiding the studs. If you can't make your model out of rectangular bricks and plates, this guy isn't interested. In fact he's positively disappointed in you, and he only grudgingly allowed plates to give you a chance. Let's see what this definition gives us:

Well, it's hard to argue with that. The proportion of a set that is just bricks and plates has indeed decreased over time. The lowest point on the graph is our old friend the orange tow truck, narrowly avoiding a 0% score with the inclusion of a solitary blue 2x3 brick. The train stations are consistently comprised of a higher percentage of bricks and plates, almost certainly because they're models of buildings, where basic bricks are clearly more likely to be found.

If we want to be slightly more generous and include slopes and tiles, the graph looks like this:

Mostly unchanged then, though the early 2000's dip becomes more apparent for the train stations.

__Conclusions__

Here are my conclusions based on what we have, and assuming the findings are representative of all sets:

- The proportion of a set that is highly specialised pieces, i.e. pieces that appear in fewer than 10 other sets is almost always less than 5%, and hasn't changed significantly over time.
- The proportion of a set that is specialised pieces, i.e. pieces that appear in fewer than 100 other sets is almost always less than 30%, and hasn't changed significantly over time.
- The proportion of a set that is just basic bricks and plates has decreased significantly over time.
- The early 2000's sucked.

Which method is better? The second method is simpler and gives more decisive results. It shows quite clearly that while it wasn't

That's the sort of thing I aim to do in future with some clever data scraping, but I have to learn how to do any data scraping at all first, so in the mean time please comment with any feedback or criticism or impassioned defences of orange tow trucks.

Part three of this series will arrive shortly, with less data and more opinions!

**all**basic bricks in the old days, sets did tend to have**more**basic bricks. On the other hand, from an AFOL's point of view, i.e. someone who isn't opposed to specialised pieces per se, as long as they aren't completely unusable for anything else, the first method is more useful. The trick is to choose the correct number of other sets a piece has to appear in to count as non-specialised. One thing I didn't do, because it would have been too time-consuming to do manually, was to exclude uses of a part in models from the same theme. For example, when looking at spaceships, if a piece has appeared in 110 other sets I would have counted it as non-specialised. But if 50 of those other sets are in the Space theme, it was probably being used for the same purpose in those other sets, meaning that it should only count as appearing in 60 other sets and therefore should count as specialised.That's the sort of thing I aim to do in future with some clever data scraping, but I have to learn how to do any data scraping at all first, so in the mean time please comment with any feedback or criticism or impassioned defences of orange tow trucks.

Part three of this series will arrive shortly, with less data and more opinions!

* To simplify the process, I count all minifigs and their constituent parts as non-specialised, regardless of how many sets they've appeared in, because the issue of minifig variety is a slightly different and more complex one than the issue we're considering here. Basically, I counted anything Bricklink defines as a regular part in a set inventory, except sticker sheets.