Research methods Lesson 3

Today Quiz on sampling Experimental design and task Qualitative and quantitative data (activity) Descriptive statistics and task Pilot studies

Sampling: Quiz – True or False? A sample is a part of the whole group of people being studied TRUE FALSE Q2 A random sample is one where anybody who is available at the time are asked at random to be in the study Q3 A volunteer sample will always be biased because volunteers are likely to be very interested in the topic being studied and/or have a specific personality type (the volunteering type) that make them atypical of people in general Q4 Opportunity samples are often used in psychological research because they are cost and time effective and because other sample types are difficult to obtain Q5 A strength of a random sample is that it is assumed that chance selection will cancel out biases and provide a sample representative of the target population Q6 “The target population” is the same as “people in general” Q7 Student samples are ideal for psychological research, especially when psychology students are used, as they take the study seriously and are convenient for researchers based in universities Stretch! For any that you believe to be false – correct the statements so that they are actually true!

Quiz – True or False? (Be honest ) A sample is a part of the whole group of people being studied TRUE FALSE Q2 A random sample is one where anybody who is available at the time are asked at random to be in the study Q3 A volunteer sample will always be biased because volunteers are likely to be very interested in the topic being studied and/or have a specific personality type (the volunteering type) that make them atypical of people in general Q4 Opportunity samples are often used in psychological research because they are cost and time effective and because other sample types are difficult to obtain Q5 A strength of a random sample is that it is assumed that chance selection will cancel out biases and provide a sample representative of the target population Q6 “The target population” is the same as “people in general” Q7 Student samples are ideal for psychological research, especially when psychology students are used, as they take the study seriously and are convenient for researchers based in universities Stretch! For any that you believe to be false – correct the statements so that they are actually true!

EXPERIMENTAL DESIGN Repeated measures design Participants take part in both conditions of the experiment (1 group) Advantages: Avoids the problem of participant variables. Fewer people are needed. Disadvantages: Order effects are more likely to occur. Demand characteristic more likely as participants might guess the aim as they take part in all the conditions. There are 3 different ways to carry out the experiment with participants. These are known as Experimental Designs. Independent measures design Counterbalancing: Alternating the order in which participants perform in different conditions of an experiment. For example, group 1 does ‘A’ then ‘B’, group 2 does ‘B’ then ‘A’ this is to eliminate order effects. Participants only take part in one condition of the experiment (2 separate groups) Matched pairs design Advantages: Avoids order effects. If a person is involved in several tests they man become bored or tired . Less demand characteristic as they do only one condition. Disadvantages: More people are needed than with the repeated measures design . Differences between participants in the groups may affect results, for example; variations in age, sex or social background. These differences are known as participant variables. Participants are matched in each condition for characteristics that may have an effect on their performance. e.g. A memory test Advantages: Reduces participant variables. Avoids order effects. Disadvantages: Very time-consuming trying to find closely matched pairs. Impossible to match people exactly. Requires more participants.

Task: Experimental design For each of the studies answer the following questions: Identify the independent variable Identify the dependent variable Identify the experimental design What strength does this experimental design have in this study? What limitation does this experimental design have in this study?

Loftus and Palmer (1974) investigated whether leading questions affect answers to speed questions. Participants were shown films of traffic accidents; all groups were shown the same films. They were then asked to give a general account of what they had just seen and asked a series of questions about it. The critical question asked was ‘About how fast were the cars going when they HIT each other?’ The word ‘HIT’ was replaced by either ‘SMASHED’, ‘COLLIDED’, ‘BUMPED’ or CONTACTED’. Each group was asked with a different word. The results suggested that participants recall was influenced by the speed word used. The word ‘smashed’ led to the fastest speed estimate (mean = 40.8 mph) and the word ‘contacted’ the slowest (mean = 31.8 mph).

Bandura et al (1961) aimed to see if behaviour that is observed will be repeated. Participants (children aged 3-5) were divided into three groups. Individuals were matched in the three groups according to their aggression levels that existed before this study began. Group one observed an aggressive adult model hitting a Bobo doll; group two observed the model acting non- aggressively and group three observed no model. All participants were then placed in a room with a Bobo doll and their behaviour was observed. Group one acted most aggressively. There was little difference between the aggression shown by groups two and three. The conclusion was that aggressive behaviour shown by a role model was imitated

Qualitative and Quantitative data Sort the statements in to those statements that describes qualitative data and those statement that describe quantitative data. Identity the strengths and weaknesses of qualitative and quantitative data

Rich in detail offering more insight into whatever is being studied Can be analysed statistically to identify trends and patterns in behaviour a goal of psychology This describes a construct Has high construct validity as in reality we would describe certain behaviours such as depression we would not give it a score or rating. This measures a construct Self-report using closed questions so that you can count the number of responses. Structured observations such as time or interval sampling where responses can be counted or rated This method is subjective and open to interpretation. This method is more reliable and objective. Correlations that measure the strength of relationships between scores. Observations where researchers describe or visually record what they see. Case studies that offer a detailed description of the person, group or situation being investigated Self-report using open questions where answers are transcribed in written form Experiments where variables are strictly measured for high levels of control.

Descriptive statistics Measure of central tendency: Mean: This is calculated by adding all the scores in a data set together and dividing by the number of scores. Mode: This is the most commonly occurring score. In some data sets, there may be more than one mode (bi- modal). Median: This is calculated by putting all the scores in a data set in order, and identifying the score in the middle. In an even numbered data set, the two middle scores are added together and divided by 2 to find the median. What are the advantages/disadvantages of each measure of central tendancy?

Strengths Weaknesses Mean Median Mode The most sensitive as it includes all the scores/values in the data set within the calculation. Due to the above point, it’s more representative of set of scores. Easily distorted by extreme values Median Not affected by extreme scores Once arranged in order the median is easy to calculate. It is not as sensitive as the mean, as not all scores are included in the final calculation. Mode Very easy to calculate Unaffected by extreme values Not very useful if there are several modes.

Descriptive statistics Measure of dispersion Range = the difference between the highest and lowest numbers (subtracting the lowest score from the highest score and (usually) adding 1 Standard Deviation = loosely defined as the average amount a number differs from the mean Variance = how spread out (far away) a number is from the mean

Descriptive statistics Measure of dispersion Standard deviation is a sophisticated measure of dispersion that shows the spread of scores around the mean. A low standard deviation means that most of the numbers are very close to the average OR in other words… The lower the standard deviation, the less spread out the scores are around the mean. A high standard deviation means that the numbers are spread out OR in other words… The greater the standard deviation, the more spread out the scores are around the mean. For example, a large SD in an experiment would mean that the participants were not all affected in the same way because the data is widely spread.

Descriptive statistics Complete the handout on descriptive statistics

Pilot studies A small scale study conducted to ensure the method will work according to plan. If it doesn’t then amendments can be made. Purpose = to help foresee any problems Whether the design works Whether participants understand the meaning of questions / wording etc Has anything important been missed out Test the validity of the study… how? Test the reliability of the study … how? Any improvements can be identified and implemented

Exam question Explain why the psychologist might want to carry out a pilot study before an observation. (2 marks) Tip: think about how we carry out an observation. Why might it be important to carry out a pilot study before conducting an observation?

Mark scheme One reason for the psychologist carrying out a pilot study would be to check that any equipment e.g. cameras were positioned appropriately. Another would be to check the suitability of the behavioural categories to ensure high internal validity.

Next week Control of variables Reliability and validity Role of peer review Psychological report Designing an experiment. Half term - graphs After half term Content/thematic analysis Carry out research Features of science