Psychology

Variables

Independant Variable- The variable that you manipulate

Dependant Variable-the variable that you measure

Extraneous Variable-undesirable variables that influence results 

Example

IV- The ampunt of spinach consumed 

DV- Strength

EV-Pre existing strength

Null hypotheses - There will be no significant difference in the strength of people who did eat spinach and those who did not eat spinach, any change will be due to chance.

Two tailed - There will be a difference is strength between those who have eat spinach and those who have not eaten spinach.

One tailed - Participants who have eaten spinach will be significantly stronger those who have not.

Advantages

• Quick and cheaper than interveiws, also Easier to display data
• Same questions asked to all participants so set procedure and can be replicated and tested for reliablity

Disadvantages

• Can obain generic answers so not always honest
• People generally do not like doing them

Strengths and weaknesses of closed ended questions

• Strength - Quantitive data can be gathered so easier to compare results
• Strength - They are the same for all paricipants so are reasonably reliable
• Weakness - Force the respondant to choose from set answers so are not accurate so not valid
• Weakness - The choice of answers can mean different things to different people

Strengths and weaknesses of open ended questions

• Strength - tend to get richer more detailed answers
• Strength - Allows for interpretation of the questions
• Weakness - Difficult to analyse because all answers are different, qualitive data so cannot display data in graphs or tables

Quantitative Data

Strengths

• Data can be summarised in graphs and tables
• Usually involve good controls so can be replicated and tested for reliablity

Weaknesses

• Specified responses so tend to not be valid
• Responses may be untruthful and participants may respond in a socially desirable way

Qualitative Data 

Strengths

• Allow more depth of analysis because of greater detail
• more valid as repondants can say what they really think

Weaknesses

• Difficult to analyse because all resonses different
• More detail and depth so will take longer for participants and researcher

Types

Structured - Follows a set format

Unstructured - questions are not in a set format so allows the interviewer to explore the area with further questions from the participants responses

Semi-Structured - has set questions some of which can be explored further by interviewer

Strengths 

• Questions can be explained and enlarged upon so good for gathering detail
• data tends to be valid because inerviewees use their own words

Weaknesses

• The interviewer may influence the data. (researcher bias)
• Analysis may be subjctive and therefore influenced by the researchers opinion