scientific processes Flashcards
what is an aim?
a precise statement on why a study is taking place/what is being studied
what is a hypothesis?
a precise testable prediction of what is expected to happen
what are the 2 types of hypothesis?
-experimental/alternative - predicts differences in the DV are beyond just chance, experimental is used only for the experimental hypothesis, alternative is used for anything else
-null hypothesis - predicts the IV won’t affect the DV, any differences are due to chance
what are the 2 types of experimental/alternative hypothesis?
-directional (one-tailed) - predicts the direction
-non-directional (two-tailed) - predicts a change will happen but doesn’t predict the direction
what is sampling?
selecting participants to represent a wider population
what are the 5 types of sampling?
-random
-opportunity
-volunteer
-systematic
-stratified
what is random sampling?
each member of the population has an equal chance of being selected
what are the strengths of random sampling?
-unbiased selection
-generalisation
what are the weaknesses of random sampling?
-impractical
-not representative
what is opportunity sampling?
selecting participants who are available and willing to take part
what are the strengths of opportunity sampling?
-ease of formation
-natural experiments
what are the weaknesses of opportunity sampling?
-unrepresentative
-self-selection
what is volunteer (self-selected) sampling?
people volunteer to participate, often by replying to adverts
what are the strengths of volunteer sampling?
-ease of formation
-less chance of the ‘screw you’ phenomenon
what are the weaknesses of volunteer sampling?
-unrepresentative
-demand characteristics
what is systematic sampling?
taking the nth person from a list, but calculating the size of the population and then what size the sample needs to work out the interval
eg 1000 population, 100 needed, every 10th person
what are the strengths of systematic sampling?
-unbiased selection
-generalisation
what are the weaknesses of systematic sampling?
-periodic traits (eg every 5th property on a street is a flat)
-not representative
what is stratified sampling?
a small-scale reproduction of the population, divided by important characteristics eg social class
what are the strengths of stratified sampling?
-representative
-unbiased
what are the weaknesses of stratified sampling?
-knowledge of population characteristics required
-time-consuming
what are pilot studies?
small-scale practice investigations to identify potential problems
