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Understanding the Basis of Statistical Power in Psychology Research Work
What is Statistical Power? The power of a statistical test for a null hypothesis is the probability of having the basis to correctly reject a false null hypothesis (Greene, 2000). Statistical power is the probability of detecting an effect if the effect actually exists or the probability that the test will lead to a conclusion that the effect actually exists (High, 2000 & Cohen, 1988, p. 4). It is also the ability of the test to report a statistically significant effect where an actual effect of a given magnitude exists. In simple terms, statistical power is the likelihood that a researcher will discover an effect of a certain size in a statistical test no matter how small. The analysis of the power of statistical test enables the researcher to estimate the ability of the entire research work to detect a meaningful effect. Technically, statistical power is the probability that the researcher will avoid a Type II error. Type II errors are false negatives where the test result indicates there is no effect when a real effect exists. The analysis of statistical power is done either retrospectively, which means post hoc, or prospectively, which implies a priori. The power of a statistical test is given as 1-β, where β (beta) is the Type II error and it is the probability that the researcher fails to reject the null hypothesis when it is false. When β is less than or equals to .2, the statistical power is said to be statistically powerful because its value would be greater than .8. According to Howell (2002), the statistical power of a test statistic like the independent t test is determined by the following three (3) parameters: 1. The size of the sample per group (N) 2. The effect size of the standardized population (d), and 3. The significance level or criterion (α) The

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## Psychology Qualitative and Quantitative Research

279 Words | 2 PagesQualitative research generates rich, detailed and valid data that contribute to in depth understanding of the context, quantitative researches generate reliable population based and generalised data. A particular strength of quantitative research is that it can be generalised to some extent, a sample that closely relates to a population is chosen. Qualitative researches do not choose samples that are closely related to a population. Quantitative researches allow the researcher to test hypotheses. Qualitative researches are more for exploratory purposes, the researches allow the data to take them on different directions.

## Value of True Experiments

992 Words | 4 PagesUniversity of Essex Department of Psychology Discovering Psychology: The science Behind Human Behaviour Discuss the value of the true experiment in psychology 1301109 24/10/2013 979 “A true experimental design as the most accurate form of experimental research, in that it tries to prove or disprove a hypothesis mathematically, with statistical analysis” Shuttleworth (2008). This means that an experimental design basically tries to see how accurate an hypothesis is through statistical analysis. So, for an experiment to be classed as a true experimental design, the sample groups must be assigned randomly, in which there must be a viable control group, only one variable can be manipulated and tested i.e. It is possible to test more than one, but such experiments and their statistical analysis tend to be large and difficult and the tested subjects must be randomly assigned to either control or experimental groups. Therefore, in a true experiment subjects are randomly assigned to the levels of the independent variable.

## Descriptive and Inferential Statistics

1010 Words | 5 PagesStatistics are a method of finding the truth and psychologist use statistical methods to help them make sense of the numbers that collect during their experiments and research and is the essence of human evolution and psychology of science. With these statistics psychologist are able to see if there theory is correct or whether they need to do more research. There are two different types of statistics that are used to draw conclusions and to describe information and they are descriptive statistics and inferential statistics

## Classroom Based Research Importance

2787 Words | 12 PagesFrom these views it can be seen that the quantitative approach is scientific based. It believes that the information already exists and is there to discover. Human perception does not play a role in the uncovering of new knowledge. A hypothesis is tested to assess its validity. Questionnaires are structured carefully in order to obtain precise information.

## Identify and Explain the Advantages of the Use of the Scientific Method in Psychology

813 Words | 4 PagesHistorical trends in psychological enquiry, in addition to fundamental shifts in Psychology’s subject base has led to the use of the scientific method. Ultimately, the aim of the scientific method is to test hypothesis by falsifying them. It is impossible to prove a hypothesis correct but we are able to prove a hypothesis wrong. Karl Popper saw falsifiability as a black and white definition, that if a theory is falsifiable, it is scientific, and if not, then it is unscientific. Empirical data is information that is gained through a direct observation or an experiment rather than a reasoned argument or unfounded belief.

## Five Steps to Hypothesis

451 Words | 2 PagesSince the parameter is a population mean of a continuous variable variable, this suggests a one sample test of a mean. 2. SPECIFY THE NULL AND ALTERNATIVE HYPOTHESES. The second step is to state the research question in terms of a null hypothesis (H0) and a alternative hypothesis (HA). The null hypothesis is the population parameter, µ = $30,000 (H0: µ = $30,000).

## What is Scientific Reasoning

268 Words | 2 PagesScientific reasoning is the process, which provides evidence for scientific theory. Induction is common throughout scientific reasoning since scientists’ use inductive reasoning whenever a limited data is used to form more general conclusions (Okasha, 2002). Induction is used to decide whether claims about the world are justified. Inductive reasoning is prevalent throughout science since it is common to have a sample size that does not include all of the possible test subjects needed for the study. This leaves the possibility that one of the test subjects not included in the sample could prove the conclusion to be incorrect.

## Heteroskedasticity Essay

1030 Words | 5 PagesThe Heteroskedasticity Problem in Regression Analysis Recall that one of the assumptions of the OLS method is that the variance of the error term is the same for all individuals in the population under study. Heteroskedasticity occurs when the variance of the error term is NOT the same for all individuals in the population. Heteroskedasticity occurs more often in cross-section datasets than in time-series datasets. Consequences of Heteroskedasticity: 1. the estimates of the b’s are still unbiased if heteroskedasticity is present (and that’s good), 2. but, the s.e.’s of the b’s will be biased, and we don’t know whether they will be biased upward or downward, so we could make incorrect conclusions about whether the X’s affect Y 3. the estimate of S.E.R. is biased, so we could make incorrect conclusions about model fit Detecting Heteroskedasticity: 1.

## Can Intelligence Change?

4853 Words | 20 PagesCan intelligence change? To what extent is intelligence malleable? Extended Essay: Psychology Name: Candidate number: School: Nörre Gymnasium Word count: 37811 Abstract This essay investigated the research question: To what extent is intelligence malleable? It was necessary to start by presenting the debate on defining intelligence since there is not a complete consensus among psychologists, however, this paper accepted a definition which is generally accepted by respected psychologists; that ‘intelligence is the ability to deal with cognitive complexity’ (Gottfredson, 1998). In presenting and analysing empirical evidence such as Howe (1997) supporting the thesis that intelligence can, in fact, change under the right conditions and given enough time, a strong indication of malleability is provided.

## Evaluate the Usefulness of the Psychometric Approach for Understanding Intelligence (24 Marks)

1078 Words | 5 PagesThis paper will evaluate the usefulness of the psychometric approach for understanding personality and human intelligence. Psychometric tests were first created in order to objectively measure intelligence and personality (Eysenck, 1994; Hayes, 2000; Hothersall, 2004; Engler, 2009). As such, it can be said that the psychometric approach for understanding personality and human intelligence is useful as it enables psychological researchers to quantitatively measure intelligence and personality in a scientific manner. Furthermore, such an approach allows for individuals be to placed in categories based on definable characteristics, which better allows psychological research on different subjects, as participants of psychological research can be more easily assigned to different groups or conditions. Thus, the psychometric approach for

### Psychology Qualitative and Quantitative Research

279 Words | 2 Pages### Value of True Experiments

992 Words | 4 Pages### Descriptive and Inferential Statistics

1010 Words | 5 Pages### Classroom Based Research Importance

2787 Words | 12 Pages### Identify and Explain the Advantages of the Use of the Scientific Method in Psychology

813 Words | 4 Pages### Five Steps to Hypothesis

451 Words | 2 Pages### What is Scientific Reasoning

268 Words | 2 Pages### Heteroskedasticity Essay

1030 Words | 5 Pages### Can Intelligence Change?

4853 Words | 20 Pages### Evaluate the Usefulness of the Psychometric Approach for Understanding Intelligence (24 Marks)

1078 Words | 5 Pages