IB Biology SL

controlled variable (constant)

something that is kept the SAME in all groups of experiment

control group

something that does not have IV / is under normal conditions. baseline → compare

independent variable (IV)

something that you change / want to experiment

dependent variable (DV)

something that you're measuring / data

experimental groups

groups which are being experimented on, levels of IV w/o control

levels of IV

different conditions based on the IV, "different types of..”, etc.

repeated trials

amount of times experiment was conducted the SAME way

mean

average

standard deviation

fluctuation of data / precision

t-test

is there a stat diff? - compare means of mult datasets

null hypothesis

skeptic - no stat diff!

alt hypothesis

is a stat diff

degrees of freedom (df)

(n-2), n = number of data pts — numbers that can change

probability (p-value)

likelihood of coincidence / luck - (# of times outcome was produced/total # of outcomes)

critical value

requirement data must pass in order to be significant → determines rejection of hypothesis

error bars

represent variability / standard dev / range on graph