Trade Price Improvement

Trade Price Improvement is a stat: When this person acts as a trade negotiator, buy and sell prices are improved by this percentage. Its default value is 100%.

Factors

It is is affected by the following:

Social: 0% plus 1.5 per skill level.
Talking: 90% weight, allowed defect of 0.05 and a max at 100%, meaning improvement over 95% does not affect trade prices.
Hearing: 90% weight, allowed defect of 0.20 and a max at 100%, meaning improvement over 80% does not affect trade prices.
Upon installing Psychic reader on a pawn, 10% of the pawn's Psychic Sensitivity is added to the base value.
Giving the leader role to a pawn provide a +2% to the base value.

It is not affected by pawn beauty, nor Social Impact buffs such as from the bowler hat.

Social Skill	T.P.I.	Sell Price	Buy Price
0	0.0%	60%	140%
1	1.5%	60.9%	137.9%
2	3.0%	61.8%	135.8%
3	4.5%	62.7%	133.7%
4	6.0%	63.6%	131.6%
5	7.5%	64.5%	129.5%
6	9.0%	65.4%	127.4%
7	10.5%	66.3%	125.3%
8	12.0%	67.2%	123.2%
9	13.5%	68.1%	121.1%
10	15.0%	69%	119%
11	16.5%	69.9%	116.9%
12	18.0%	70.8%	114.8%
13	19.5%	71.7%	112.7%
14	21.0%	72.6%	110.6%
15	22.5%	73.5%	108.5%
16	24.0%	74.4%	106.4%
17	25.5%	75.3%	104.3%
18	27.0%	76.2%	102.2%
19	28.5%	77.1%	100.1%
20	30.0%	78%	98%

Trade Price Improvement Milestones

The list below shows the milestones of T.P.I.:

The minimum T.P.I. a pawn can have is 0%
Without DLCs the maximum T.P.I. a pawn can have is 30% with a Social skill of 20.
A T.P.I. of 40% is the maximum value you should aim for selling stuff since the game prevents the selling price from being lower than the purchase price so higher T.P.I. mean selling for less. (This is the point where the selling price is equal to the buying price, 84% of the market value)
A T.P.I. of 44.23% is the highest value you can reach in the game with DLCs. To achieve this value you need a pawn with Social skill of 20, the leader role, the Psychically Hypersensitive trait, the implants Psychic sensitizer and Psychic reader, a Legendary Eltex staff, Eltex skullcap, Eltex robe, Eltex vest and Eltex shirt.
A T.P.I. higher than 100% is useless since the minimum buying price is $0.50.

Maximizing Trade Price Improvement

The Trade Price Improvement can only be maximize by installing Psychic reader on your pawn and improving it's Psychic Sensitivity since you are stuck at 30% with only the Social skill.

An easy way to get to 40% T.P.I. is to use a pawn with a burning passion for Social and the Psychically Hypersensitive trait. Then you need to assign this pawn as your leader and buy/find a Psychic sensitizer, a Psychic reader, a good Eltex staff and an excellent Eltex shirt to get exactly 40% T.P.I at a Social skill of 20.

If you manage to get a T.P.I. higher than 40% you can literally get everything traders haves for free. As an example, all traders buy Insect jelly, so you can sold it for $6.72 a piece at 40% T.P.I. then buy it back at $6.50 a piece with a T.P.I. of 42%.

Exact value use in Trade

When you trade your T.P.I. in the top left corner is rounded to the nearest integer. To see the reel T.P.I. that is use for calculation go in the information tab of the pawn.

The price of items shows went trading in rounded to the nearest integer or the second decimal if the price in lower than $10, but the exact value is use for the total price calculation. For example selling Insect jelly with a Social skill of 0 will show a buy price of $11 even if the game use the exact price (8*1.4=$11.20) so buying 3 Insect jelly will cost $34 instead of $33 as the total price of a trade is always rounded to the nearest integer.

Stats