Key Science Skills

controlled variables

held constant to ensure changes in DV are solely due to IV

controlled experiment

a type of investigation where the effect of the IV on the DV is testing while aiming to control all other variables

case study

an in-depth investigation on a particular topic

correlational studies

a type of non-experimental study in which researchers observe and measure the relationship between two or more variables without any active control or manipulation of them

an advantage of using a within-subjects design

ensures results are due to independent variables then any differences between participants that would occur if they were in seperate groups

a disadvantage of using a within-subjects design

it can produce order effects

an advantage of using a between-subjects design

does not create order effect

a disadvantage of using a between-subjects design

differences between participants across groups can affect results

an advantage of using a mixed design

allows experimenters to compare results across experimental conditions and across participants

a disadvantage of using a mixed design

can be more costly and time consuming to plan, conduct and analysis

3 types of sampling

convenience sampling, random sampling and stratified sampling

convenience smapling

any sampling technique that involves selecting readily available members of the population

an advantage of convenience sampling

time and cost effective

a disadvantage to convenience sampling

can produce unrepresentative sample

random sampling

any sampling technique that uses a procedure to ensure every member of the population has the same chance of being selected

an advantage of random sampling

reduces experimenter bias in selecting participants

a disadvantage of random sampling

time consuming to ensure every member of a population has an equal chance of being selected

stratified sampling

any sampling technique that involves selecting people from the population in a way that ensures that its subgroups are proportionally represented in the sample

an advantage of stratified sampling

produces most representative data

a disadvantage of stratified sampling

time consuming and expensive

extraneous variable

any variable that is not the independent variable but may cause an unwanted effect on the dependent variable, before experiment and can be controlled by controlled variables

confounding variables

a variable that has affected the dependent variable, apart from the independent variable, after experiment that was due to not being controlled and now it connotes be determined if caused was IV or the confounding variables

7 types of confounding variables

Participant-related variables, order effect, placebo effect, experimenter effect, situational variables, non-standardised instructions and producers, and demand characteristics

Participant-related variables

characteristics of participants that may affect results

how to deal with participant-related variables

increase sample size to create more representative

Order effect

the tendency for the order in which participants complete experimental conditions to have an effect on their behaviour

how to deal with order effect

counterbalancing which is where groups within within experimental groups complete each condition in a different order

Placebo effect

when participants response to an inactive treatment

how to deal with placebo effect

single-blind procedure which is were the participant is unaware of what experimental group they have been allocated to

Experimenter effects

when the expectations of the researcher affect the results of an experiment

how to deal with experimenter effects

double-blind procedures which is when both participant and experimenter do not know which condition participant has been allocated to

Situational variables

any environmental factor that may affect the dependent variable

how to deal with situational variables

standardised testing conditions and procedures

Non-standardised instructions and procedures

when directions and procedures differ across participants or experimental conditions

Demand characteristics

cues in an experiment that may signal to a participant the intention of the study and influence their behaviour

measures of variability and 2 types of measures

statistics that summarise and describe the spread and distribution of a data set. Range and standard deviation

standard deviation

a measure of variability, expressed as a value that describes the spread of data around the mean

what does a high and low standard deviation mean

low means high accuracy

high mean high inconsistency

accuracy

how close a measurement is to the true value of the quantity being measured

precision

how closely a set of measurement values agree with each other

systematic errors

errors in data that differ from the true value by a consistent amount

how to overcome systematic errors

adjust to correct use

what do systematic errors affect

accuracy

random errors

errors in data that are unsystematic and occur due to chance

how to overcome random errors

repeat measurements

what do random errors affect

precision

Personal errors

errors made by researchers

uncertainty in data

the lack of exact knowledge relating to something being measured due to potential sources of variation in knowledge

repeatability

the extent to which successive measurements or studies produce the same results when carried out under identical conditions within a short period of time

reproducibility

the extent to which successive measurements or studies produce the same results when repeated under different conditions

internal validity

the extent to which an investigation truly measures or investigates what it claims to

Interval validity can be achieved by

adequate measurement tools, experimental design, sampling and whether the independent variable truly affected dependent variables

external validity

the extent to which the results of an investigation can be applied to similar individuals in different settings

External validity can be improved by…

using representative sampling, having broad inclusion and larger sample size

5 ethical concepts

beneficence, integrity, respect, justice and non-maleficence

beneficence

commitment to maximising benefits and minimising risks and harm

integrity

commitment to honest reporting

justice

obligation to ensure that there is fair consideration of competing claims

respect

consideration of the extent to which living things have a value

non-maleficence

principle of avoiding causing harm

6 ethical considerations

confidentially, informed consent procedures, deception, debriefing, withdrawal rights and voluntary participation

confidentiality

the privacy, protection and security of a participant’s personal information

informed consent procedures

processes that ensure participants understand the nature and purpose of the experiment

deception

the act of intentionally misleading participants about the true nature of a study

debriefing

ensures that, at the end of the experiment, the participant leaves understanding the experimental aim, results and conclusions

voluntary participation

ensures there is no pressure to partake in an experiment

withdrawal rights

the right of participants to be able to discontinue their involvement in an experiment at any time