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Sampling…. When we carry out research we need people to take part, these people are called P_ _ _ _ _ _ _ _ _ _ _ and the group of people used is referred to as the S _ _ _ _ _. Target population?. Target Population.
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When we carry out research we need people to take part, these people are called P_ _ _ _ _ _ _ _ _ _ _ and the group of people used is referred to as the S _ _ _ _ _.
Target population? Target Population • The target population is the group of people that the researcher wishes to draw conclusions on. • Can psychologists study the whole target population… Definition: The target population is the total group of individuals from which the sample might be drawn.
Target Population Complete task 1 on your handouts. What is the target population in the following studies? a. A study of attitudes of social democrat voters to NHS reform. b. Research into a cure for the fear of spiders. c. An experiment to investigate the effects of separation in infant monkeys. d. A study of prejudice amongst white South Africans. e. Research into the use of specially adapted cookers for blind people. Answer – Social democrat voters Answer – Individuals with a fear of spiders Answer – Infant monkeys Answer – White South Africans Answer – Blind people Definition: The target population is the total group of individuals from which the sample might be drawn.
Representative & Generalisation • Psychologists use sampling techniques to choose people to representthe target population. • If your sample is representative then you can generalise the results of your target population. = Sample Target Population
Questions Using the key terms we have encountered so far, answer the following questions in your exercise (pink) books. Key Terms: Representative, Unrepresentative, Generalisation, Target Population. • What is a ‘ biased sample’? • What can’t you do with bias samples? • What is a ‘representative sample’? • What can you do with representative samples?
Sampling Techniques • We will now examine some of the sampling techniques used by Psychologists to obtain participants for their sample.
Opportunity Sampling • Opportunity sampling consists of selecting anyone who is available & willing to take part in the study. Common Room Who wants to be in my study… No way…
Random Sampling • This is a sampling technique which is defined as a sample in which every member of the target population has an equal chance of being chosen. This involves identifying everyone in the target population and then selecting the number of participants you need in a way that gives everyone an equal chance of being selected.
Volunteer Sampling • Volunteer sampling consists of participants becoming part of a study because they volunteer when asked or in response to an advert. I just love to be helpful…. Sounds rubbish… Volunteers needed for psychological study on learning Psych Lab… Gotta do my hair… I’ve always wanted to be in a study….
Applying & Evaluating Sampling Complete the following tasks, in the order below, by following the instructions on your handouts! • Task 3 – Types of sampling: Different ways to select your participants; • Task 2 – Identify the sampling method used; • Task 4 – Evaluating samples.
Task 2 – The Answers A researcher wished to study memory in adults aged 18-65yrs. He stands in the high street of a town and stops people as they pass. A university department undertook a study of mobile phone use in adolescents, using a questionnaire. The questionnaire was given to a group of students in a local comprehensive school, selected by placing all the students’ names in a container and drawing out 50 names. A class of psychology students conducts a study on memory. They put a notice on the sixth form notice board asking for students who have an hour to spare. Answer – Opportunity sampling Answer – Random sampling Answer – Volunteer sampling
Task 4 – The Answers 1. Why are volunteer samples hardly ever representative? 2.Why are opportunity samples hardly ever representative? 3.Why are random samples mostly representative of the target population? Answer – Particular type of person offers to take part in research, thus sample is likely to be bias (can’t generalise to rest of population). Answer – High chance that sample will be biased. E.g., often use available university students, which are not representative of the target population. Answer – The sample is likely to be representative so can be generalised to the target population, as everyone has an equal chance of being select.
Aim & Hypotheses Objective • To understand and apply the following research methods to psychological investigations: • Aim • Directional hypothesis • Non-directional hypothesis
What is the AIM of the study? • The aim of the study is what the researcher is trying to find out. • A research question is decided and then the researcher considers his/her aim. For example: • The research question: Does hunger affect memory? • The aim: To see if hunger affects memory.
What is the hypothesis? • Once the researcher has an aim, they need to state their hypothesis. • A hypothesis is a prediction about the variables in the study. For example – Hunger leads to better memory of food related words.
The hypothesis • The hypothesis SHOULD show the INDEPENDENT VARIABLE and the DEPENDENT VARIABLE. Hunger leads to better memory of food related words • What is the independent variable in this study? • What is the dependent variable in this study? Answer – Hunger. Answer – No. of food related words correctly recalled.
Directional/Non Directional • Directional hypothesis: • For example – Hunger will increase the number of food related words correctly recalled. • Non-directional hypothesis: • For example – Hunger will have an effect on the number of food related words correctly recalled. What’s the difference between directional & non-directional? • (Note, that the hypothesis does not state whether or not the number of words recalled will be more/less).
Aim, IV, DV, One & Two-Tailed… Task 5: State the aim, IV, DV and an appropriate one-tailed and two tailed hypothesis for each of the following research questions: • Does the weather affect mood? • Do boys and girls like different music? • Do we lose our memory as we get older? • Can a person be conditioned to fear spiders? • Is there less attention in classes on a Friday afternoon? • Is there such a thing as a born killer? Task 6: If you complete the above work through task six: . Underline the IV; 2. Circle the DV; 3. Decide whether the following are directional or non-directional hypotheses. Extension: Now change the hypotheses around so that the directional becomes the non-directional and vice versa.
Plenary - The Tedious Link • Using ALL the key words in today’s lesson, explain how these words are all connected, in one paragraph. Each word has to be EXPLICITLY linked to the previous, as above. Therefore, in each new sentence you must include the previous key word and how it links to the new one… Key words: Aim, Research Question, IV, DV, Hypothesis, One-tailed, Two-tailed, Target Population, Sample, Random, Opportunity, Volunteer For example, the IV is the variable that is manipulated to examine the effect this has on the DV. The DV is what the researcher is measuring in order to examine his hypothesis…
Experiment 1 - Recap An experimenter wants to see if drug X improves sport performance. One group are given the drug, another are given a placebo. Both groups are tested for athletic ability. • Identify the IV and DV; • Identify the experimental condition and the control condition.
Experiment 2 - Recap A researcher is interested in whether alcohol has an effect on memory. One group of participants are given a list of words to learn and then given an alcoholic drink. The other group is given the same list of words, and a glass of water. The number of words they can remember is recorded. • Identify the IV and DV; • Identify the experimental condition and the control condition.
Experiment 3 - Recap A psychologist is investigating the effect of music on concentration. A group of participants are given a series of crossword puzzles to solve, first in a silent room, then when classical music is played, and then when rock music is played. The time taken to solve each puzzle is recorded. • Identify the IV and DV; • Identify the experimental condition and the control condition.
Experiment 4 - Recap A scientist has developed a drug which he believes will increase IQ. He has two groups of participants; one group he gives the drug to, and the other he gives a placebo to. After two weeks, he tests their IQ. To try and avoid any participant variables, he ensures that he has an equal number of men and women in each group, and that the participants are of similar ages, intelligence and social background. • Identify the IV and DV; • Identify the experimental condition and the control condition.
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