Experimental methods

Question 1

what are the different types of variables?

Answer 1

• Independant variable
• Dependant variable
• Extraneous variables
• Confounding variables

Question 2

What is an independant variable?

Answer 2

• variable that the researcher manipulates in order determine its effect on the dependant variable = experimental conditions
  e. g. 20g chocolate, 10g of chocolate and no chocolate (control condition)

Question 3

what is the control condition?

Answer 3

to provide a standard against which experimental conditions can be compared, there may be a control condition where IV is not manipulated

e.g. no chocolate

Question 4

what is the dependant variable?

Answer 4

this is the variable that is being measures

Question 5

what are extraneous variables?

Answer 5

these are any other variables other than the IV that COULD affect the DV

e.g. how tired (sleep), food + drink (hunger), weather

Question 6

what are confounding variables?

Answer 6

these are any variables other than the IV that HAVE affected the DV

e.g. light, noise

Question 7

what is operationalisation?

give an example

Answer 7

variable needs to be defines + stated how it will be measures

e.g. operationalise the term happiness:
happiness is a feeling of content/how positive someone is
this can be measured by how many times someone smiles in a 10 minute period

Question 8

what are the different types of experiments?

Answer 8

1. laboratory experiments
2. field experiments
3. natural experiments
4. quasi experiments

Question 9

describe laboratory experiments

Answer 9

• experiment is carried out in a controlled environment e.g. lab = allows high level of control over IV + eliminate EV
• researcher can observe + measure change in DV caused by manipulation of IV
• carried out in an artificial setting
• participants are randomly allocated (unpredictable way) to a condition
• experimenter wants to hold EV constant to minimise impact on results
• EV e.g. participant’s personality/ personal experiences

Question 10

what are the ads of a laboratory experiment?

Answer 10

• very high level of control over the IV and conditions = easy to control for any extraneous variables + prevent them from becoming confounding variables that can affect the measurements of data collected
• researcher can measure/manipulate the IV + establish a cause and effect relationship between the IV and DV
• the experiment can be easily repeated/replicated by other researchers to see if similar results can be obtained = if so, then it’s reliable

Question 11

what are the disads of a laboratory experiment?

Answer 11

• demand characteristics may occur = participants may guess what the aim of the study is and change their behaviour accordingly so the data becomes invalid e.g. parts may behave in a more positive light than normal = social desirability bias
• establishing a high level of control over IV and EV can mean that the experimental situation can lack mundane realism (extent to which the experiment reflects real life) –> lab study doesn’t have ecological validity (ability to generalise findings to other real life situations/places/contexts)

Question 12

what are field experiments?

Answer 12

• experiment carried out in real world or natural setting rather than in an artificial setting of lab
• IV is manipulated/controlled by researcher to see effect on DV

e.g. observe people in street

Question 13

what are the ads of a field experiment?

Answer 13

• there is more mundane realism + ecological validity than in a laboratory = reflects real life more than a lab experiment
• because the researcher can manipulate the IV, a cause and effect relationship between the IV and DV can be established
• less chance of demand characteristics compared to lab experiment = in a field experiment, parts may not even be aware that they’re taking part in research so they’ll behave more naturally = more valid data collected

Question 14

what are the disads of field experiments?

Answer 14

• less control over EV when compared to lab experiment
  = effect on DV may not be caused by IV but by EV
  –> means that research is not valid (not measuring what it intends to research)
• less control over sample = sample may not be representative of target population
• may be difficult to replicate which means they may be unreliable compared to lab experiments

Question 15

what is a natural experiment?

Answer 15

• researcher takes advantage of a naturally occurring IV to see its effect on the DV
• measures variables that aren’t directly manipulated by experimenter = IV naturally occuring
• experimenter is finding parts who have already met the conditions of the experiment rather than allocating parts to conditions themselves

Question 16

what are the ads of natural experiments?

Answer 16

• high level of mundane realism + ecological validity
• very useful when it is impossible or unethical to manipulate the IV/sample in lab or field experiment
• e.g. study a naturally occurring even that would otherwise be unethical to impose on participants

Question 17

what are the disads of a natural experiment?

Answer 17

• low level of control over EV
• very difficult to replicate = very unreliable + if experiment was repeated, then inlikey same results
• difficult to determine cause and effect due to low levels of control

Question 18

what is a quasi experiment?

Answer 18

• naturally occurring IV
• naturally occurring IV is a difference that already exists e.g. gender, age etc..
• researcher examines the effect of IV on DV
• usually take place in lab

Question 19

what are the ads of quasi experiments?

Answer 19

• high level of control = effects of EV are minimised = experiment an be more confident that it is the IV that’s affecting the DV
• replication is very likely due to strict controls = easier to replicate to test reliability

Question 20

what are the disads of quasi experiments?

Answer 20

• lack of ecological validity = setting is artificial = experiemnt snot a reflection of real life
• demand characteristics may be a problem = parts may eithr accurtaely or inaccurately guess aim of experiment and respond acording to what they think is being investigated =affects data being collected = invalid study