EXPERIMENTATION
Validity Variables controlled so that any measured effect is likely to bedue to the independent
variable
Reliability consistent values in repeats and independent replicates
Accuracy Data or means of data sets are close to the true event
Precision Measured values are close to eachother
2 a Pilot Study
◦A pilot study is integral to the development of a scienti c investigation.
◦The purpose of the pilot study is to develop and improve experimental protocols, ensuring
that the experimental design is suitable for investigating the aim and hypothesis.
◦The use of pilot studies is necessary to avoid wasting signi cant time and money on full-
scale investigations using awed experimental methods.
◦A pilot study should be used to provide information and data on a number of parts of
experimental design, as summarised below.
Importance of a pilotstudy
Intergral to the development of an investigation a pilotstudy
is used to help PLAN PROCEDURES ASSESS VALIDITYand
CHECK TECHNIQUES
This allows for EVALUATION and MODIFICATION of
EXPERIMENTAL DESIGN
The use of a pilotstudy can ensure an APPROPRIATE
RANGEOFVALUES FORTHE INDEPENDENT VARIABLE
in addition it allows the
invetigator to establish the
number of REPEAT MEASUREMENTS REQUIRED to give
a REPRESENTATIVE VALVE each independent
for
datum point
Identify and control CONFOUNDING VARIABLES
Develop a NEW PROTOCOL or enable an investigator to BECOME PROFICIENT is using an
established protocol
Check whether results can be produced in a SUITABLE TIMEFRAME
, 2 b Experimental Design
i Independent 31 Dependent Variables
In an experiment, the experimental treatment group is compared to a control group. However, in
any biological experiment, there is usually a large number of factors that can change, known as
variables. Experimental variables can be spit into three types; independent, dependent and
confounding.
Independent Variable the variable that is deliberately changed by the investigator to determine if it
has an effect on the outcome of the experiment
Dependent variable a variable that is measured to determine if changing the independent variable
has an effect
Experiments involve the manipulation of the independent variable and measuring of the
dependent variable
by the investigator
Variables can be classed as either discrete or continuous data
DISCRETE VARIABLES
have FINITE VALUES that allow placement into SEPERATE GROUPS
For example sex blood groups 31 eye colour
CONTINUOUS VARIABLES
chang gradually from ONE EXTREME TO ANOTHER potentially having an
INFINITE NUMBEROF POSSIBLE VALUES
Forexample height age 31 solution concentration
TYPES OFEXPEXPERIMENTAL DESIGN
Experiments can be simple, changing only one independent variable, or multifactorial, changing more
than one independent variable.
Validity Variables controlled so that any measured effect is likely to bedue to the independent
variable
Reliability consistent values in repeats and independent replicates
Accuracy Data or means of data sets are close to the true event
Precision Measured values are close to eachother
2 a Pilot Study
◦A pilot study is integral to the development of a scienti c investigation.
◦The purpose of the pilot study is to develop and improve experimental protocols, ensuring
that the experimental design is suitable for investigating the aim and hypothesis.
◦The use of pilot studies is necessary to avoid wasting signi cant time and money on full-
scale investigations using awed experimental methods.
◦A pilot study should be used to provide information and data on a number of parts of
experimental design, as summarised below.
Importance of a pilotstudy
Intergral to the development of an investigation a pilotstudy
is used to help PLAN PROCEDURES ASSESS VALIDITYand
CHECK TECHNIQUES
This allows for EVALUATION and MODIFICATION of
EXPERIMENTAL DESIGN
The use of a pilotstudy can ensure an APPROPRIATE
RANGEOFVALUES FORTHE INDEPENDENT VARIABLE
in addition it allows the
invetigator to establish the
number of REPEAT MEASUREMENTS REQUIRED to give
a REPRESENTATIVE VALVE each independent
for
datum point
Identify and control CONFOUNDING VARIABLES
Develop a NEW PROTOCOL or enable an investigator to BECOME PROFICIENT is using an
established protocol
Check whether results can be produced in a SUITABLE TIMEFRAME
, 2 b Experimental Design
i Independent 31 Dependent Variables
In an experiment, the experimental treatment group is compared to a control group. However, in
any biological experiment, there is usually a large number of factors that can change, known as
variables. Experimental variables can be spit into three types; independent, dependent and
confounding.
Independent Variable the variable that is deliberately changed by the investigator to determine if it
has an effect on the outcome of the experiment
Dependent variable a variable that is measured to determine if changing the independent variable
has an effect
Experiments involve the manipulation of the independent variable and measuring of the
dependent variable
by the investigator
Variables can be classed as either discrete or continuous data
DISCRETE VARIABLES
have FINITE VALUES that allow placement into SEPERATE GROUPS
For example sex blood groups 31 eye colour
CONTINUOUS VARIABLES
chang gradually from ONE EXTREME TO ANOTHER potentially having an
INFINITE NUMBEROF POSSIBLE VALUES
Forexample height age 31 solution concentration
TYPES OFEXPEXPERIMENTAL DESIGN
Experiments can be simple, changing only one independent variable, or multifactorial, changing more
than one independent variable.
