Reliability and Validity

What is the definition of internal and external validity?

• Internal- the study measures what it intends to measure bc cofounding variables are controlled

• External- whether the study reflects real life behaviours

Give 3 examples of reliability issues and explain

• Lack of operationalisation of variables - precisely defining and measuring variables

• Order/ practice effect (in repeated measure design) - While completing 2nd condition ptp may become better at task or underperform due to boredom.

• Lack of standardised procedures - Accuracy of measuring and uncontrolled environment can jeopardise reliability.

Give 2 ways to deal with internal reliability

• Using standardised procedure, scienftifics measure equipment and conducting research in lab can help overcome most reliability problems

• Order effects can be resolved with counterbalancing which involves splitting sample into 2 the first half of sample complete condition 1 and 2nd half complete condition two then they switch.

How can external reliability be dealt with?

• Test- retest: Study is repeated with same participants, if test is similar both times the test is said to have external reliability

• Inter rated reliability - 2 or more psychologists produce consistent results by using standardised procedures and check for agreement between data

• Split half - splitting ptp test answers in half and seeing weather they got the same or similar scores on the two halves. If so high internal reliability

What is meant by internal and external reliability ?

• Internal - Extent to which study is consistent within itself

• External - Extent to which study produces consistent results over many occasions

What are 3 examples of validity issues?

• Researcher bias - Researcher directly or indirectly influences results of study

• Demand characteristics - participants work out aim of study and begin to behave differently.

• Social desirability - Participants give responses they think will show them in the best possible light.

Give 3 ways to deal with different validity issues

• Improve sample method - use sampling method that is more representative

• Researcher bias - Use of double blind procedures neither researcher or participant involved know the true aims of the study

• Social desirability & Demand characteristics - Use of single blind procedures, ptp Is unaware of aim until the end.