SW Score measures the influence a particular keyword has on the entire project within which you are tracking it.
There are 4 ways you can mark the weight of your keywords in SerpWatch:
None—Keywords will be ignored and not used in the equation
Low—Low weight keywords will have a very low impact on the project ranking; each keyword with this weight will improve the general position of the project by 1 if its position is better than the position that’s generated by the algorithm, and will worsen the position of the project by 1 if the position is worse
Default—upon creating a project, each keyword has the default weight; in this case, it will be used in the equation and will have a mid-range influence on the project
High—High weight will flag the most important keywords in the project and it will influence general position the most.
Each weight type will signal the importance of your keywords to the success of the entire project.
It’s calculated based on the position and the search volume associated with a particular keyword. The higher the position the keyword reaches and the bigger search volume it has, the better of the entire project.
By the same token, even if your keyword reaches a high ranking position, but has low search volume, you won’t see as big of a change. Always have in mind that both factors will influence the movement you see in the chart.
While the ranking is the most obvious criterion by which you may measure the success of your keyword and, ultimately, project, have in mind that getting to that #1 position may mean nothing if no one is searching for that term.
Also, please note that search volume is a highly volatile value which makes it practically impossible to showcase precisely in continuation.
Ultimately, the amount of impact it actually has on the project depends on the user and is set via the SW Score. The SerpWatch equation is there to give you a picture of how specific keywords fare in relation to the entire project they are part of.