3.2 Flashcards
pilot study
a preliminary small scale study conducted to help decide how best to conduct a large scale research project.
independent variable
variable that is changed or controlled in a scientific experiment
dependent variable
variable tested and measured in a scientific experiment
confounding variable
variable which affects the dependent variable that is not the independent variable
continuous variation
characteristic that can be measured and it shows a wide range occurring between two extreme measurements
discrete variation
characteristic that shows a definite number of easily observed clear-cut types
quantitative data
data that is measured (eg. numbers)
qualitative data
data that is observed (eg. colour)
ranked data
observations put in order from smallest to largest
positive control
treatment that is included to check that the system can detect a positive result when it occurs
negative control
provides results in the absence of a treatment
precision
the closeness of repeated measurements to one another
accuracy
a measure of how close the data, or means of data sets, are are to the true value
validity
all confounding variables controlled so that any measured effect is likely to be due to the independent variable.
reliability
consistent values in repeats and independent replicates
in-vivo
an investigation carried out using a living organism e.g. mouse model organism
in-vitro
an investigation carried out using biological molecules or cells out with their normal biological system e.g. cell culture
simple experimental design
experimental design where only 1 independent variable is changed at a time
multifactorial experimental design
experimental design is more complex and involves a combination of more than one independent variable or combination of treatments
randomised block
minimise the effects of when confounding variables cannot easily be controlled
observational studies
the independent variable is not directly controlled by the investigator, for ethical or logistical reasons
causation
when changing the independent variable causes the effect noted in the dependent variable
representative sample
should share the same mean and the same degree of variation about the mean as the population as a whole
stratified sampling
the population is divided into categories that are then sample proportionally
random sampling
members of the population have an equal chance of being selected
systematic sampling
members of a population are selected at regular intervals
placebos
placebos can be include as a treatment without the presence of the independent variable being investigated
placebo effect
a measurable change in the dependent variable as a result of a patient’s expectations, rather than changes in the independent variable.
box plots
used to show variation within and between data sets
mean
the arithmetical average, add all values and divide by the number there are of them
median
the middle point from the range of values
mode
the most common values in a set of data
correlation
a connection between the variables and does not imply causation
strength of correlation
is proportional to the spread of values from the line of best fit
positive correlations
exists when and increase in one variable is accompanied by an increase in the other variable
negative correlations
exists when an increase in one variable is accompanied by a decrease in the other variable
