How will running change your chance of finding a wild Pokemon?

Question

As in a percentage.

Comments

i was so ready to answer this until i saw the question info -_-

Answer 1

Only in HGSS, running increases your chances of encountering a Pokemon by 2 (regular grass and caves) or 1.33 (tall grass).

In Pokémon HeartGold and SoulSilver, running increases one of the variables used for spawning wild encounter by 20 - effectively doubling it in regular tall grass or while in a cave, and increasing it by one third in long grass, with the latter ending up higher than the rate while riding a Bicycle (70). This increase is not present in Pokémon Diamond, Pearl, and Platinum; however, the encounter rates are higher in these games (40 and 70, respectively, instead of 20 and 60).

Running Shoes (Bulbapedia)

Answer 2

There is a woman in HeartGold who says that if you run through grass you are more likely to "startle" Pokemon as you are making more noise. However, I don't think that running actually increases the number of Pokemon in the grass, nor does it increase the chance that one will appear when you hit each square.

If you are running you are covering squares more quickly, so you should run into a Pokemon sooner. Assuming running speed is twice as fast as walking, it would take about half the time on average to find a Pokemon. (That would also suggest maybe a third or quarter of the time if you are cycling, but in my experience that doesn't seem to be the case.)