Sentiment phrases can either be a regular phrase up to 4 words long, or they can use the full Boolean query syntax. For example, to tune the concept of "small screen" as a negative, you can use either:
|small NEAR/3 screen||-0.5|
The first form matches only the exact phrase "small screen" while the second form matches text such as "The screen is pretty small."
The weighting of a phrase should be between 1 and -1. We use this scale:
Phrases also obey negators and intensifiers, such as not and very. Because of this, you should usually not enter a negated phrase such as "not good." Enter the phrase that carries the sentiment (good) and let the NLP engine figure out the negation.
Single words are often somewhat context-dependent for their sentiment. Think carefully about using single words. For instance, you might see a sentence like "This product is garbage" and want to enter "garbage" by itself as a negative phrase. However, garbage is also used in non-sentiment contexts, such as "garbage truck" or "take out the garbage." If "garbage" is much more often than not used in a sentiment way in the content in your domain, put it in your dictionary but it pays to think twice about single words.