Example 2: A psychology study investigated whether people tend to display more creativity when they are thinking about intrinsic (internal) or extrinsic (external) motivations (Ramsey & Schafer, , based on a study by Amabile, ). The subjects were 47 people with Statistics forms the basis of scientific approach to problems of Educational Psychology. Meaning of Graphical Representation of Data: A graphic representation is the geometrical image of a set of data This document contains general guidelines for the reporting of statistics in psychology re-search. The details of statistical reporting vary slightly among different areas of science and also among different journals. General Guidelines Rounding Numbers For numbers greater than , report to the nearest whole number (e.g., M = ). For
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Tables are devices for presenting data simply from masses of statistical data. Tabulation is the first step before data is used for analysis. Tabulation can be in form of Simple Tables or Frequency distribution statistics for psychology i. They are useful methods in presenting simple statistical data.
Diagrams are better retained in the memory than statistical tables. They are merely a way of presenting a set of numbers by the length of a bar. The bar chart can be simple, multiple or component type. It is a pictorial diagram of frequency distribution. It consists of a series of blocks. The class intervals are given along the horizontal axis and the frequencies along the vertical axis.
A frequency distribution may be represented diagramatically by the frequency polygon. It is obtained by joining the mid-points of the histogram blocks. Instead of comparing the length of a bar, the areas of segments of a circle are compared. The area of each segment depends upon the angle. Small pictures or symbols are used to statistics for psychology the data. It gives a mental picture of the central value. It is an average of a different kind, which does not depend upon the total and number of items.
To obtain the median, the data is first arranged in an ascending or descending order 0 of magnitude, statistics for psychology, and then the value of the middle observation is located.
The range is by far the simplest measure of dispersion. It is defined as the difference between the highest and lowest figures in a given sample. If we have grouped data, the range is taken as the difference between the midpoints of the extreme categories. It is the most frequently used measure of deviation.
It is denoted by Greek statistics for psychology 6. When the sample size is more than 30, statistics for psychology above basic formula may be used without modification, statistics for psychology. For smaller samples, the above formula tends to underestimate the standard deviation, and therefore needs correction i.
The larger the standard deviation the greater the dispersion of values about the mean. The normal distribution or normal curve is an important concept in statistical theory. The shape of the curve will depend upon the mean and standard deviation which in turn will depend upon the number and nature of observation. The area between one S, statistics for psychology. The area between two Statistics for psychology. on either side of the mean will cover most of the values i.
The area between three S, statistics for psychology. will include Although there is an infinite number of normal curves depending upon the mean and S. It is a smooth, bell shaped perfectly symmetrical curve based on an infinitely large number of observations, statistics for psychology.
The total area of the curve is 1, its mean is 0 and its S. The mean, median and mode all coincide. The distance of a value x from the mean X̅ of the curve in units of S. This is done by assigning a number to each of the units the individuals in the sampling frame. Random numbers are a haphazard collection of certain numbers, arranged in a running manner to eliminate personal selection of unconscious bias in taking out the sample.
This technique provides the greatest number of possible samples, statistics for psychology. This is done by picking every 5th or 10th units at regular intervals. By this method, each unit is the sampling frame would have the same chance of being selected, but the number of possible samples is greatly reduced.
The sample is deliberately drawn in a systematic way so that each portion of the sample represents a statistics for psychology strata of the universe. This method is particularly useful where one is interested in analysing the data by a certain characteristic of the population e.
If we take repeated samples from the same population or universe, the results obtained from one sample will differ to some extent from the results of another sample. This type of variation from one sample to another is called sampling error. It occurs because data were gathered from a sample rather than from the entire population of concern, statistics for psychology. The factors which influence the sampling error are size and variability of individual readings. Errors may occur due to inadequate calibrated instruments, due to observer variation as well as due to incomplete coverage achieved in examining the subjects selected and conceptual errors.
If we take a random sample from the population, and similar samples over and over again, statistics for psychology, we will find that every sample will have a different mean. The S. of the mean is also called the standard error and the distribution of the sample means about the true mean of the universe. This is called to set confidence limits and find out level of significance, statistics for psychology.
To compare the results between two groups e. This is done by calculating the standard error of difference between the two means. Instead of means, sometimes one has to test the significance of difference between two proportions or ratios to find out if the difference between the two proportions or ratios have occurred by chance.
Chi-square x 2 test statistics for psychology an alternate method of testing significance of difference between two proportions. It has advantage that it can be used when more than two groups are to be compared.
First, one has to set up a hypothesis, called the Null Hypothesis that there was no difference between the findings of the two groups. Measures the statistical relationship between two sets of variables, without assuming that either is statistics for psychology or independent. Measures relationship between two sets of variables but assumes that one is dependent and the other is independent.
Assume a normal distribution e. Non parametric statistics use data which are not normally distributed e. Looks for the minimum number of dimensions which can be used to define a group. This will generate dimensions e. Factors are an expression of the relationship between attributes, not between individuals. A very reliable test may have low validity precisely because its results do not change i. Information is called by document studies case notes, journal articles, census etc. Any extraneous variable whose potential influence on the dependent variable has not been controlled for.
A source of error e. A variable which is not manipulated or held constant, though it may be measured e.
Intro to Psych Statistics
, time: 53:18Department of Psychology | CSU
Statistics forms the basis of scientific approach to problems of Educational Psychology. Meaning of Graphical Representation of Data: A graphic representation is the geometrical image of a set of data Psychology and statistics. Statistics in everyday life. Some examples where intuition is misleading, and statistics is critical. Chapter 2: A brief introduction to research design. Basics of psychological measurement. Reliability and validity of a measurement. Experimental and non-experimental design Descriptive statistics employs a set of procedures that make it possible to meaningfully and accurately summarize and describe samples of data. In order for one to make meaningful statements about psychological events, the variable or variables involved must be organized, measured, and then expressed as quantities
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