L8 - Control of Extraneous Variables Flashcards
why must EXTRANEOUS VARIABLES be controlled?
in order to ensure that a STUDY HAS VALIDITY, EXTRANEOUS VARIABLES MUST BE CONTROLLED for to PREVENT THEM FROM BECOMING CONFOUNDING VARIABLES
what are the 4 TYPES of EXTRANEOUS VARIABLES? (PIED)
(P) Participant Variables
(I) Investigator Effects
(E) Environmental Variables
(D) Demand Characteristics
what are PARTICIPANT VARIABLES? - PT 1
these are CHARACTERISTICS of the PPS which MAY AFFECT THE DV (e.g intelligence, age, gender)
Choosing an APPROPRIATE EXPERIMENTAL DESIGN can help to try and OVERCOME THESE VARIABLES. MATCHED PAIRS and REPEATED MEASURES can help to avoid PP VARIABLES. However, repeated measures can LEAD TO ORDER EFFECTS, so COUNTERBALANCING SHOULD BE USED TO AVOID THIS
what are PARTICIPANT VARIABLES? - PT 2
RANDOM ALLOCATION of pps to conditions when using INDEPENDENT GROUPS should ALSO ENSURE THAT GROUPS ARE NOT BIASED. However, RANDOM ALLOCATION is NOT POSSIBLE for a QUASI EXPERIMENT
The PROCESS OF RANDOM ALLOCATION involves ALL THE PPS being IDENTIFIED BY EITHER NAME OR NUMBER. The names are put in a HAT or a COMPUTER and then randomly assigned to either condition until there are the REQUIRED NUMBER in EACH CONDITION.
what are ENVIRONMENTAL VARIABLES?
these are FACTORS in the ENVIRONMENT WHERE the EXPERIMENT IS CONDUCTED that COULD AFFECT THE DV (e.g temperature, lighting, noise)
The answer to this is STANDARDISATION (i.e making sure that ALL THE CONDITIONS, MATERIALS and INSTRUCTIONS are the SAME FOR ALL PPS)
what are INVESTIGATOR EFFECTS? - PT 1
this is when the PERSON COLLECTING THE DATA has KNOWLEDGE of what the RESEARCH AIM IS and that knowledge AFFECTS THE DATA OBTAINED
OBSERVER BIAS is a type of INVESTIGATOR EFFECT. INVESTIGATOR EFFECTS can be OVERCOME BY THE DOUBLE BLIND TECHNIQUE - this is when NEITHER THE PPS nor the the INVESTIGATOR know the HYPOTHESIS OF THE STUDY or WHAT CONDITION THE PP IS IN
what are INVESTIGATOR EFFECTS? - PT 2
INVESTIGATORS may INADVERTENTLY INFLUENCE THE RESULTS OF THEIR RESEARCH. Certain PHYSICAL CHARACTERISTICS of the investigator, such as AGE, GENDER, and ETHNICITY can INFLUENCE THE BEHAVIOUR OF PPS.
STANDARDISED SCRIPTS should be written to ENSURE THAT THE INVESTIGATOR ACTS IN A SIMILAR WAY WITH ALL PPS. The investigator should also be TRAINED to GREET ALL PPS IN THE SAME WAY and ASK THEM QUESTIONS IN A NEUTRAL TONE.
what are DEMAND CHARACTERISTICS? - PT 1
One COMMON EXTRANEOUS VARIABLE is DEMAND CHARACTERISTICS. There are MANY FEATURES of RESEARCH STUDIES that may ENABLE PPS TO GUESS A STUDY’S PURPOSE and what is EXPECTED OF THEM.
This can LEAD TO THE PP TRYING TO PLEASE THE RESEARCHER by giving the ‘RIGHT’ RESULTS, trying to annoy the researcher by giving the ‘wrong’ results (SCREW YOU EFFECT), acting UNNATURALLY out of NERVOUSNESS, or acting OUT OF SOCIAL DESIRABILITY BIAS, OBSERVER EFFECTS and INTERVIEWER EFFECTS are TYPES OF DEMAND CHARACTERISTICS
what are DEMAND CHARACTERISTICS? - PT 2
DEMAND CHARACTERISTICS can be OVERCOME by the SINGLE BLIND TECHNIQUE. This involves making sure pps DO NOT KNOW WHAT THE HYPOTHESIS IS or WHAT CONDITION THEY ARE IN.
This is MORE DIFFICULT TO ACCOMPLISH when using a REPEATED MEASURES DESIGN
