Key terms and concepts

• Demand characteristics occur when the participants try to make sense of the research and act accordingly to support the aim of the research.
• Demand characteristics are an issue, as the participants may behave in a way to support the hypothesis, making the results less valid.
• Conversely, the participant may deliberately try to disrupt the results, a phenomenon known as the 'screw-you' effect.
• In an experiment, the dependent variable (DV) is the variable that the researcher measures.
• The dependent variable (DV) is the variable that is affected by the manipulation of the independent variable (IV).
• Descriptive statistics analyse data to help describe, show or summarise it in a meaningful way.
• A directional hypothesis is a one-tailed hypothesis that states the direction of the difference or relationship (e.g boys are more helpful than girls).
• The discussion is the section of a report where the researcher interprets the results of the study; makes criticism of the methodology used; considers the implications of the results for future research, and suggests real-world applications.
• Ecological validity is a type of external validity that refers to the extent to which the findings can be generalised to a real-life setting.
• An empirical method involves the use of objective, quantitative observation in a systematically controlled, replicable situation, in order to test or refine a theory.
• Event sampling is used to sample behaviour in observational research.
• Experimental design describes the way participants are allocated to experimental groups.
• Types of experimental design include repeated measures, independent groups, and matched pairs designs.
• Extraneous variable (EV) is a general term for any variable, other than the IV, that might affect the results (the DV).
• Face validity is a simple way of assessing whether or not something measures what it claims to measure, which is concerned with its face value, e.g

  does an IQ test look like it tests intelligence?
• Falsifiability is an important feature of science.
• Field experiments are carried out in natural conditions, in which the researcher manipulates the independent variable (IV) to measure the effect on the dependent variable (DV).
• Generalisation is the application of the results from a study, to the wider target population.
• A histogram is a type of graph used for continuous data (e.g

  age)
• A hypothesis is a testable prediction about the variables in a study.
• Hypothesis testing is an important feature of science, as this is how theories are developed and modified.
• Independent groups design is an experimental design where different participants are used in each condition of the experiment.
• Random allocation should be used to decide to which condition each participant should be allocated, as this ensures that each participant has an equal chance of being assigned to one group or another.
• In an experiment, the independent variable (IV) is the variable that the researcher manipulates and is assumed to have a direct effect on the dependent variable (DV).
• Inter-observer reliability is very important to establish when conducting observational research.
• Inter-observer reliability refers to the extent to which two or more observers are observing and recording behaviour in the same way.
• Interval level data is data measured in fixed units with equal distance between points on the scale, such as temperature measured in centigrade.
• Interviews are a type of self-report technique that involve an interviewer asking questions, generally on a one-to-one basis, and recording responses.
• There are different types of interview: structured (where the interviewer has a set list of questions with which to lead the conversation and a framework which will be rigidly adhered to), semi-structured (where the interviewer may have a list of topics or questions, but has extra flexibility to develop the conversation further, should participant responses lead to deeper/more detailed discussion), and unstructured (which are more like a conversation with no set questions).
• The introduction is the section in a report/journal where the researcher reviews previous research (theories and studies) to provide background information and a rationale for the current research.
• Investigator effects are where a researcher (consciously or unconsciously) acts in a way to support their prediction, which can be a particular problem when observing events that can be interpreted in more than one way.
• Laboratory experiments are conducted under controlled conditions, in which the researcher manipulates the independent variable (IV) to measure the effect on the dependent variable (DV).
• In psychology, there are different ways that variables can be measured and psychologists typically group measurements into one of four scales: nominal, ordinal, interval or ratio.
• The Mann-Whitney U test is a non-parametric statistical test of difference that allows psychologists to determine if their results are significant, used in studies that have an independent groups design, where the data collected is at least ordinal.
• Matched pairs design is an experimental design where pairs of participants are matched in terms of key variables, such as age and IQ, one member of each pair is then placed into the experimental group and the other member into the control group.
• The mean is a measure of central tendency that is calculated by adding all of the scores in a data set and dividing by the total number of scores, it is the most sensitive measure of central tendency as it includes all of the scores in its calculation, but is easily distorted by extreme values.
• Measures of central tendency are descriptive statistics that depict the overall 'central' trend of a set of data, there are three key measures: mean, median and mode.
• Measures of dispersion describe the spread of data around a central value (mean, median or mode), they tell us how much variability there is in the data, there are two measures of dispersion: range (where you subtract the lowest score from the highest score) and standard deviation (SD) - which calculates the spread of scores around the mean.
• The mode is a measure of central tendency which is calculated by reporting the most frequently occurring number in a data set, while it is easy to calculate, it is of little use where the data set includes many different numbers.
• A meta-analysis is where researchers combine the findings from multiple studies to draw an overall conclusion.