on what base does the visa officer grant visa or reject

[Jets13]

ok lets say that is fair, but what about the the point they raise for the refusal? is it fair?

i don't think so, leaving your husband and young child back home are strong ties in my opinion. Plus you seem to have a job where you travel quite a bit and if you did intend to overstay you could have done it already at all the countries you visited.