In a within-subjects research study, factors that change over time, such a history and maturation, can be threats to

i thought a 14 year old should know this but

colonies   were tied to britain through trade and by the way they were governed.   trade was restricted so the colonies had to rely on britain for imported goods and supplies.   there were no banks and very little money, so colonists used barter and credit to get the things they needed.  

britain also needed money to pay for its war debts.   the king and parliament believed they had the right to tax the colonies.   they decided to require several kinds of taxes from the colonists to pay for the french and indian war.   these taxes included the stamp act, passed in 1765, which required the use of special paper bearing an embossed tax stamp for all legal documents.   other laws, such as the townsend acts, passed in 1767

this mainly outraged the colonies and created what we know as today as the american revolutionary war