Yes in horse racing the odds are lower when the outcome is more likely since there is less of a payout. If for example a horse has a lower chance of winning a bet would give out more money. A 10/1 odds means that a bet of 1 dollar will give the winner gets 10 but if is 5/1 the winner only gets 5 because that horse had a better chance of winning. The same concept carries over here. In short if you are betting on things and something becomes more likely to happen the odds go down.