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PSYCH 101- STATISITICS IN PSYCHOLOGY MODULE 2
EXAM 2025-2026| 38 QUESTIONS AND ANSWER|S
RATED A+
Descriptive statistics They describe and summarize a set of scores. They often tell us what a typical score is (mean) and how spaced out the scores are (standard deviation) inferential statistics When you infer characteristic about a population using a sample. Population The complete set of scores or observations. Sampling error The discrepancy observed between a sample set of scores (sample statistic) and the population parameter that the sample was drawn from.
Sample A subset of scores or observations that were drawn from the population. Mean A statistic that describes the central tendency of a set of scores by being all of the scores added divided by the number of scores (mathematical average). Population is mu and sample is M. Standard Deviation A statistic that describes the variability in a set of scores. It is the average amount that each score deviates from the typical score. Correlation coefficient A statistic that describes both the direction and the magnitude of the relationship between 2 variables. Example: How related are height and weight.
Parameter (define and greek/roman symbol) Describes the aspects of a population and is represented by mu or u. It is like a characteristic. What is the equation for sampling error? The mean of the sample minus the mean of the population as an absolute value. It will always be positive. Do differing samples from the same population have the same sample error? Yes. They differ from both each other and the population. Central tendency a measure that represents the typical response or the behavior of a group as a whole Three ways to measure central tendency mean, median, mode
Mode (define) The most frequently occurring number in a set of data. There can be multiple modes or no mode at all. When is the mode best used? It is used for qualitative data, like categories, that math cannot be performed on. Ex. Grade 2 class's favorite color. When is mean best used? It is best used for quantitative data, that math can be performed on. The data should also be evenly distributed throughout the population and is often graphed as a bell curve. It has the least level of sampling error. Median the middle score in a distribution; half the scores are above it and half are below it. if the data set is an even number then it is the average of the two middle scores.
In a population use ___________ symbols and in a sample use ____________ symbols. population is greek and sample is roman. How is standard deviation calculated? the square root of the variance (which is where all of the raw scores are subtracted from the mean, and then all of the answers are squared, added together, and then divided by the number of scores. This is then square rooted). Variability (how is it measured?) How spread out a set of scores is. Commonly measured with standard deviation. If the variability is ------ then all of the scores are close together and if it is ----- they all of the scores must be spread apart. low-close together high-spread apart
What is the symbol for the correlation coefficient? The roman letter 'r' Scatter Plot A graph with points plotted to show a possible relationship between two sets of data. each point is a single measurement on two variables. Positive correlation A correlation where as one variable increases, the other also increases, or as one decreases so does the other. Both variables move in the same direction. negative correlation as one variable increases, the other decreases. Ex. the number of absences vs high school grades The sum of the __________________________ is always zero. deviation scores
