Visions is a small set with 62 commons, 55 uncommons, and 50 rares. This is a new size for small sets. The set was printed in the USA and Belgium.
Visions was sold in 15 card booster packs. Booster boxes have 36 packs.
There are also Visions preview packs that have different booster art. The collation of such packs is excepted to be different than ordinary Visions.
The US printing uses sequential collation with 10 × 11 sheets. Packs are back-facing and contain 11 commons, 1 rare, and 3 uncommons (in that order).
|11 Commons||1 Rare||3 Uncommons|
There are three common runs, A, B, and C. Runs A and B contain 30 and 25 cards respectively. (Cards appear twice in each run, so these are probably the top and bottom halves of a full sheet.) Run C contains 7 cards. Two different pack formats have been observed. Most packs have 5 cards from A, 5 cards from B, then 1 card from C. A few packs have 8 cards from A and 3 cards from C. (Note, this kind of pack has only been observed once so far, but something like this is also required by the math.) Assuming these are the only pack types, we can calculate the rate of each based on the ratio of A and B cards (since the printing rate of C cards is somewhat uncertain). Mathematially, the rate of the packs with no B cards should be 1/9. If this is correct, C cards would get 11/9 cards per pack on average. However, I believe this is probably not correct.
If we take the Belgian printing as a clue, we can hypothesize that the C run is printed on the top half of the rare sheet. But, unlike the Belgian printing, there is more than one C card per pack, so we can guess that the sheet actually has 110 cards instead of 100 cards like the Belgian printing. If this is true, then C should get 6/5 cards per pack (which is slightly less than the 11/9 number). To achieve this ratio, we need to introduce a new pack type. My guess is 9 cards from A and 2 cards from C. (This is far from certain.) Under this hypothesis, packs with 8 A cards appear 1/11 of the time and packs with 9 A cards appear 1/55 of the time.
Given that A and B cards are equally rare (which should be true if they are printed on the same sheet), and that C cards appear at a 6/5 rate, it turns out C commons are slightly more rare than A and B commons. (This does not depend on the exact pack configuration that gives 6/5.) On average, C commons will be 330/343 as common as A and B commons. However, C commons are probably not equally likely, as seven does not go evenly into likely sizes of the C run. Given my guess of a length 60 C run, there will probably be 3 cards that appear 8 times and 4 cards that appear 9 times. Then, compared to A and B commons, these will be 44/49 and 99/98 as likely, respectively. (This means C commons that appear 9 times in the run should be slightly more common than A and B commons.)
Run A contains 30 cards each twice. Cards are in a repeating color pattern of white, black, red, green, blue. The choice of first card is mostly arbitrary.
Run B contains 30 cards each twice. Cards are in a repeating color pattern of white, blue, black, red, green. The choice of first card is mostly arbitrary.
The layout of run C is not known, but it contains Python, Goblin Swine-Rider, Warthog, Infantry Veteran, Inspiration, Phyrexian Walker, and Sisay's Ring.
The Belgian printing uses striped collation with 10 × 11 sheets and 10 × 10 sheets. Packs are back-facing and contain 3 uncommons, 1 rare, and 11 commons (in that order).
|3 Uncommons||1 Rare||11 Commons|
There are two groups of commons. Most commons are in group B which consists of 55 commons, each printed twice on a 10 × 11 sheet. The remaining 7 commons are in group A. The first common in every pack is from group A, and the rest are from group B.
It is very unlikely that (excluding errors) any pack contains more or less than one A common. This is because A commons are printed on the top half of a 10 × 10 rare sheet. This mean they are printed at the same rate as rares which also appear one per pack. However, this means that A and B commons do not have the same rarity. Overall, A commons that appear 7 times on the sheet are 77/100 as common as B commons, and the common that appears 8 times (Sisay's Ring) is 88/100 as common.
There are pictures of all three sheets. 
Group A is printed on the top half of the rare sheet. (See below for the bottom half containing the rares.) It contains 6 cards each seven times plus Sisay's Ring eight times. Note that the cards that appear in this group are not exactly the same as the cards that appear in run C from the US printing.
Group B consists of 55 cards each appearing twice on a sheet.
Each of the 55 uncommon cards appears twice on the sheet.
Each of the 50 rares appears once on the sheet. Note that the top half of this 10 × 10 sheet consists of the commons from group A.
 The Gamepedia wiki has pictures of the Belgian common, uncommon, and rare sheets.