Science skills

Hypothesis

tentative prediction of experiment outcome- based on existing theory, links dependent and independent variables

Hypothesis format

It is predicted that, if the (dependent variable) is affected by the (independent variable), then (effect on DV) when (change in IV)

Independent variable

purposely changed by researcher

dependent variable

changes in response to independent variable, measured

controlled variables

not investigated, kept constant

controlled experiments

examine one variable at a time, require a control group

reliability

ability to obtain same results if experiment is repeated

replication

whole experiment repeated with same methodology-checks for reliability

repeated trials

several trials conducted and results averaged-checks for reliabilty

quantitative data

data collected about numerical variables

continuous data

takes any value within a range e.g age, temperature, height

discrete data

can only take certain values e.g number of chromosomes

qualitative data

data about categorical variables e.g colour, breed

tables

used to collect data, IV should be in left column and DV in right column

graphs

allow you to see trends in data, IV on x-axis, DV on y-axis, use evenly spaced scale

line of best fit

shows trends, even number of points above and below line

outliers

data point that doesn’t follow pattern, should be plotted on graph, but can be bypassed by line of best fit

evaluating data

results should be averaged to reduce uncontrolled variables influence, outliers should be discussed

validity

tests what is meant to be tested, well designed, collects accurate and reliable data