Research Methods Sampling Techniques Being a Psychologist The

Research Methods Sampling Techniques

Being a Psychologist The purpose of research is to create results which can be generalised beyond the participants of the study. Target population The group of people we wish to investigate. Can be specific (nurses, schizophrenics etc) Could be all humans!

If your research sample is properly constructed this gives you an ability to generalise any results and conclusions about them onto the target population from which your sample came

Random Sampling Every member of a population has an equal chance of being selected. Everyone in the target population is available for selection each time a participant is picked out. E. g. Pulling names out of a hat

Stratified Sampling Dividing the target population into important subcategories Selecting members in proportion that they occur in the population E. g. 2. 5% of British are of Indian origin, so 2. 5% of your sample should be of Indian origin… and so on

Volunteer Sampling Individuals who have chosen to be involved in a study. Also called self-selecting E. g. people who responded to an advert for participants

Opportunity sampling Simply selecting those people that are available at the time. The way participants are selected is not structured. E. g. going up to people in cafés and asking them to be interviewed

Evaluation Random sampling- strengths No bias in the way p’s are chosen and therefore a more representative sample The findings can be easily generalised to the target population and detailed conclusions drawn Weaknesses It’s often difficult to make sure everyone in the target population is available for the study creating bias Can be more time consuming than opportunity or volunteer due to having to identify all people within the target population

Evaluation Stratified- strengths Conclusions between the subgroups can be made due to an equal percentage taken from each group Weaknesses It is difficult to identify how many p’s should be taken from each group Identifying subgroups within the target population may mean that some subgroups may be ruled out which may mean the sample isn’t representative

Evaluation Volunteer Strengths More ethical than other sampling methods due to the p’s approaching the researcher Volunteers are interested in the study and less likely to give biased answers Disadvantages Can be time consuming to wait for p’s to respond Volunteers may be very similar i. e. in Milgram’s study all of the p’s responded from the newspaper ad and therefore all read the same publication

Evaluation Strengths Ethical because researchers can decide whether p’s are suitable to take part Quick and easy to collect p’s in comparison to volunteer or stratified Weaknesses Increased chance of a biased sample as the researchers just choose people who are available Researchers may struggle to find willing p’s

Think about your variables IV: E. G. Teaching method that participants take part in DV: Measure of reading ability ( scores from tests) Extraneous variables: Unwanted variables, ow would you control them?

Things to consider What experimental design are you going to use and why? What is your target population? What sampling technique are you going to use and why?

Standardised Instructions Standardisation means keeping everything the same for all participants so that the investigation is fair. For example, consider the instructions that are given to the participants. In order to ensure that all of the participants get precisely the same instructions, the experimenter should write them down. He or she should then either read them to the participants, or ask the participants to read them to themselves. This makes sure that the experiment is fair, and we can be sure that the IV is the variable that has affected the DV

Standardised Instructions To ensure that all participants have the same experience, researchers should ensure that they are all tested: • In the same place, with the same equipment and materials placed in the same way. • Under the same conditions, so the level of lighting, noise and heat remains the same for all participants. • At roughly the same time of day, as people may behave differently if tested at nine o'clock in the morning rather than five o'clock at night. • Given identical standardised instructions in exactly the same way.

Standardised Instructions “If at any time you feel uncomfortable and wish to leave the experiment you may do so. If at the end of the experiment you wish your results to be removed, they can be. All results will be kept in the strictest confidence. 1. Open envelope one and remove the sheet inside (sheet one). 2. Look at the list of pictures and words shown. 3. When you are told to do so replace sheet one back inside the envelope, and reseal it. 4. Turn over sheet two and read the instructions. 5. Once you have completed the experiment, hand all the sheets and envelopes in. 6. After completing the experiment, please do not discuss the experiment with any other participant. “

these are given in the chosen location and there may be more than one set for different (IV) conditions of the investigation. The standardised instructions are important, as each participant must receive the same instructions so they understand what to do in the study. Also, it ensure that each participant is treated the same and should help eliminate experimenter effects. You can read the instructions to the participant(s), or let them read the instructions themselves.

Briefing Briefing: what is said to a prospective participant. At the end of this the person agrees to take part (i. e. gives their consent) or refuses. Make sure the brief includes the aim of your study (e. g. what is being investigated). For example: “I am a psychology student conducting a study investigating language. The study would only take 5 minutes of your time. You results would be confidential. Would you like to take part? ”

Debriefing this is where all is explained to the participant who is thanked at the end of his/her contribution. Makes sure the aim of your study is included and also a reference to ethical guidelines. Make sure in your debriefing statement that you refer to participant’s results being confidential. Next, make sure that participants’ names are not showed/written on the results sheets, raw data or anywhere else in the report (re: confidentiality). The best thing to do here is to cross them out. Again, you can read the instructions to the participant(s), or let them read the instructions themselves.

Debriefing Thank you for taking part in this experiment. The aim of this study was to investigate the effects of language (i. e. two different lists of words) on the reproduction of a series of abstract figures (pictures) i. e. the effect of language on thought. This was done by splitting the participants into two groups. Each group saw a different list of words. If after reproducing the picture they are distorted towards their given verbal labels then the experiment will show the language effects thought. Please remember that your results are confidential and you can choose to withdraw your results at any time. Do you have any questions? ”

What other materials will you need?

What you need to do Please fill out the hand-out which will be provided