# Shared Flashcard Set

## Details

Quantitative Methods
Final Study Guide
145
Psychology
12/05/2011

Term
 Statistics
Definition
 a field in mathematics that deals with the organization, analysis, and presentation of numerical information
Term
 Constant
Definition
 a characteristic or value that does not change, but rather is the same in all situations
Term
 Variable
Definition
 a characteristic that can take on different values, either across individuals at a single point in time or within a given individual at different times
Term
 Construct
Definition
 a characteristic that cannot be observed directly, but which manifests itself in observable behaviors
Term
 Operational Definition
Definition
 the process of defining a given construct in terms of a specific set of measurements taken on observable behaviors or events associated with that construct
Term
 Data
Definition
 numerical information resulting from measurement of a behavioral science characteristic
Term
 Dataset
Definition
 a collection of data with a common basis, such as information collected in a research study or scores on some test.
Term
 Population
Definition
 the entire collection of everyone who possesses a given characteristic or a specified combination of characteristics
Term
 Parameter
Definition
 any numerical characteristic or feature of a population
Term
 Sample
Definition
 any subset of a given population
Term
 Statistic
Definition
 any numerical characteristic or feature of a sample
Term
 Descriptive Statistics
Definition
 the process of organizing and summarizing data
Term
 Inferential Statistics
Definition
 the process of forming conclusions about a population based on results of studying a sample taken from that population
Term
 Sampling Error
Definition
 the difference between the characteristics of a sample and those of the population from which it was drawn
Term
 Discrete Variable
Definition
 a variable which is measure using either whole numbers or distinct categories with no intermediate values or levels
Term
 Continuous Variable
Definition
 a variable that can be measured (at least theoretically) with an infinite number of levels between whole values
Term
 Real Limits
Definition
 the boundary interval that surrounds a given value on the scale for a continuous variable
Term
 Nominal Data
Definition
 simple categorization of a characteristic without reference to quantity, quality, or any other consideration that would make one category "better" than another categoryExamples: hair color, major, gender, favorite food
Term
 Ordinal Data
Definition
 simple categorization of a characteristic but where reference is made to one category being more or better than anotherExamples: military hierarchy, seniority in a job, year in college
Term
 Interval Data
Definition
 numerical description of a characteristic based on a scale with equal intervalsExamples: temperature, IQ score
Term
 Ratio Data
Definition
 numerical description of a characteristic based on a scale with equal intervals and an absolute zeroExamples: weight, time, length
Term
 Laboratory Experiment
Definition
 a research method where one variable is manipulated under carefully controlled conditions in order to observe changes in a second variable
Term
 Independent Variable
Definition
 the variable that is directly manipulated in a laboratory experiment
Term
 Dependent Variable
Definition
 the variable that is observed in a laboratory experiment to determine how it was affected by changed in the independent variable
Term
 Survey
Definition
 a research method where self-reported information is collected directly from a sample of people
Term
 Informal Observation and Analysis
Definition
 research conducted to identify the essential properties, dynamics, and structures of a given situation or characteristic
Term
 Rounding
Definition
 the process of changing the results of a division to a specified number of decimal places
Term
 Decimal Position
Definition
 the numeric place where the results of a given division should end
Term
 Frequency Distribution
Definition
 a tabular display showing the number of times each score or value in a dataset occurred
Term
 Proportion
Definition
 the ratio of the number of values for one particular scale point divided by the total number of values in the dataset
Term
 Cumulative Frequency
Definition
 the total number of values at or below a given scale point
Term
 Percentile Rank
Definition
 the percentage of scores in a dataset that are at or below a particular scale value
Term
 Grouped Frequency Distribution
Definition
 a frequency distribution where scores are placed in various groups rather than being listed individually
Term
 Class Interval
Definition
 the scores or values placed together in one grouping
Term
 Scatter Plot
Definition
 a display where each axis represents a variable and each individual is represented by a point at the intersection of their scores on the two variables
Term
 Although not always possible, a good guideline is to try to have at least --- times as many total values (N) as class intervals
Definition
 five
Term
 Frequency Polygon
Definition
 a visual display made by connecting the dots with a continuous line rather than drawing bars
Term
 Stem
Definition
 the first part of a score in a stem-and-leaf plot
Term
 Abscissa
Definition
 the more formal name for the horizontal axis on a scatter plot
Term
 Relative Frequency
Definition
 the number of values at a given scale point in a grouped frequency distribution
Term
 Stem-and-Leaf Plot
Definition
 one way to present interval or ratio data that involves breaking each score into two parts
Term
 Cumulative Frequency
Definition
 the total number of values at or below a given scale point
Term
 Ordinate
Definition
 vertical axis in a scatter plot
Term
 Histogram
Definition
 graphical display that does not leave a space between the bars also good for displaying ratio data
Term
 Scatter Plot
Definition
 a display where each axis represents a variable and each individual is represented by a point at the intersection of their score on the two variables
Term
 Middle
Definition
 the percentile rank computed form a grouped frequency distribution that represents the score or person in that class interval
Term
 Bar Chart
Definition
 display that is good for showing nominal or ordinal data
Term
 Pie Charts
Definition
 visual display that is an alternative to bar charts with nominal or ordinal data
Term
 Leaf
Definition
 the last part of a score in a stem-and-leaf plot
Term
 Ten
Definition
 grouped frequency distributions should have around this many class intervals
Term
 Central Tendency
Definition
 the "middle" or "center" of a group of scores. also a primary feature of data distributions and the one that is typically described first
Term
 Variability
Definition
 how "spread out" or "dispersed" the scores are relative to the center of a distribution. Also an essential component of data description, and is a close companion to central tendency
Term
 Shape
Definition
 how a distribution of data looks when plotted as a frequency distribution. also is one of the most important yet often overlooked aspects of research
Term
 Mean
Definition
 the mathematical average of a group of score or values
Term
 Deviation Score
Definition
 the difference between any individual score and the mean of the distribution
Term
 Median
Definition
 the score that is at the 50th percentile point in a distribution
Term
 Undetermined Score
Definition
 a score for which the value is unknown, often the result of a task that the person could not complete outright or within the allotted time.
Term
 Open-Ended Score
Definition
 a characteristic which is measured with specific values up to a certain point and then with a summary category for all remaining values
Term
 Mode
Definition
 the most frequently occurring score ina distribution
Term
 Full Information Approach
Definition
 properties of data where every score is used in the computation.
Term
 Limited Information Approach
Definition
 properties of data where not all of the scores are used in the computation, which can be advantageous in certain situations
Term
 Overestimate
Definition
 when the extreme score is on the high side of the scores
Term
 Underestimate
Definition
 when the extreme score is on the low side of the scores
Term
 Outlier
Definition
 an extreme score that is present on one side of a distribution
Term
 Box Plot
Definition
 a common visual technique for detecting outliers that involves identifying the middle 50% of the data
Term
 Weighted Mean
Definition
 a mean computed such that some values are given more influence or weight than other values
Term
 Confidence Interval
Definition
 a range of values that a given parameter is likely to fall within, at least to a reasonable degree of certainty
Term
 Greek Letters
Definition
 Letters used to denote population characters
Term
 MMM
Definition
 acronym to help remember the three measure of central tendency
Term
 Variance
Definition
 the average squared distance the scores in a distribution are from the mean
Term
 Standard Deviation
Definition
 the square root of the average squared distance the scores in a distribution are from the mean
Term
 Biased Statistic
Definition
 a sample statistic that, on average, does not return the corresponding value in the population
Term
 Unbiased Statistic
Definition
 a sample statistic that, on average, does return the corresponding population parameter
Term
 Interquartile Range
Definition
 the range of values encompassing the middle 50% of a distribution
Term
 Semi-Interquartile Range
Definition
 the range of values encompassing one of the two middle 25% segments of a distribution, either from the 25th to the 50th percentile or from the 50th to the 75th percentile
Term
Definition
 the range computed after an extreme value, one that does not fit with the general trend of the rest of the date, is removed
Term
 Computational Formula
Definition
 Formulas that do not show the inner nature of the standard deviations ad variance, but rather provide an efficient means to compute them
Term
 Definitional Formula
Definition
 formulas that show how the standard deviation and the variance operate mathematically
Term
 RSV
Definition
 acronym that can be used to help remember the three measure of variability
Term
 Range
Definition
 one of the three measure of variability that is the most sensitive to extreme scores. also a limited information approach
Term
 Modality
Definition
 the number of areas in a distribution with a heavy concentration of scores, which is a key aspect of the characteristic being studied because one with a single area of concentration is very different than one with two or most such areas
Term
 Line Chart
Definition
 a graphical display with a continuous line showing the frequency to which various scores in a distribution occurred. it shows the same data as the frequency distribution from which it was created, just in a different way.
Term
 Symmetry
Definition
 the degree to which the pattern of frequencies for one half of a distribution is a mirror image of that for the other half
Term
 Skew
Definition
 a condition where there are a small number of extreme values residing on one side of a distribution
Term
 Slope/Kurtosis
Definition
 how quickly the frequency drops off as you move away from the center of a distribution
Term
 Leptokurtic
Definition
 a specific form of kurtosis, one in which the frequency drops quickly as you move away from the center of a distribution
Term
 Platykurtic
Definition
 a specific form of kurtosis, one in which the drop in frequency is gradual as you move away form the center of a distribution
Term
 Mesokurtic (Bell-shaped)
Definition
 a specific form of kurtosis where the drop in frequency is gradual as you move away from the center, then steep, and then gradual again
Term
 Trimodal
Definition
 distribution that has three distinct peaks
Term
 Bell-Shaped
Definition
 the informal name for a mesokurtic distribution
Term
 J-Distribution
Definition
 distribution that looks somewhat like the top-end portion of a normal curve
Term
 Extreme Scores
Definition
 occurs when the center is closer to one end of a scale with fixed limits
Term
 Transformation
Definition
 changing the way a set of data looks without changing the basic properties of that data
Term
 Standard (z) Scores
Definition
 resulting values when a distribution is transformed to have a mean of zero and a standard deviation of one
Term
 z-score
Definition
 the number of standard deviations that a score is away from the mean of its distribution
Term
 z-score
Definition
 the number of standard deviations that a score is away from the mean of its distribution
Term
 Deciles
Definition
 a transformation based on percentile rank where each grouping of 10% of the scores (e.g. 10-20) is assigned a number from 1 to 10.
Term
 84th Percentile
Definition
 score that is one standard deviation above the mean
Term
 Frequency
Definition
 the height of a curve at any scale point that represents to which that point occurred
Term
 95% of scores
Definition
 found in the range bounded by the mean plus two standard deviations on the high side and the mean minus two standard deviations on the low side
Term
 Percentile Rank
Definition
 the percent of scores below a given score
Term
 50% of the scores
Definition
 one half of a normal distribution
Term
 68% of scores
Definition
 % of sores found in the range bounded by the mean plus and minus one standard deviation
Term
 47.5% of scores
Definition
 % of scores in a normal distribution will fall between the mean and two standard deviations on either side of it
Term
 Inferential Statistics
Definition
 the process of forming conclusions about a population based on results of studying a sample taken from it
Term
 Sampling Bias
Definition
 condition where the sample that is being tested is different in distinct and identifiable ways from the population to which an inference is being made
Term
 Sampling Error
Definition
 the condition where the sample that is being tested is not totally representative of the population to which an inference is being made due to random chance in the sampling process
Term
 Null Hypothesis Significance Testing
Definition
 one of two major methods for making inferences about populations based on sample data
Term
 Null Hypothesis
Definition
 formal statement that there is no effect of difference in the population for the characteristic being studied
Term
 Two-Tailed Alternate Hypothesis
Definition
 a prediction that there is an effect or difference in a target population, but without reference to the specific direction or nature of that difference
Term
 One-Tailed Alternate Hypothesis
Definition
 prediction that incorporates a specific direction for the effect or difference
Term
 Test Statistic
Definition
 a single value which summarizes the results of a given reseach study
Term
 Standard Error of the Mean
Definition
 the denominator of the z (and t) test statistic for a one-sample test
Term
 Critical Value of a Test Statistic
Definition
 the value of a test statistic that corresponds to a specified level of chance probability
Term
 Alpha
Definition
 the critical level of probability at which we change our inference from the absence of an effect in the target population to the presence of an effect
Term
 Degrees-of-freedom
Definition
 a concept from basic math referring to the number of scores that are free to vary after some critical feature of a group of numbers is specified
Term
 Type I Error
Definition
 occurs when a researcher incorrectly concludes there is an effect in the target population when in reality there is not. only applicable when the null hypothesis is rejected
Term
 Type II Error
Definition
 when a researcher incorrectly concludes there is not an effect in the targe population when in reality there is one. only applicable when the null hypothesis is retained
Term
 Power
Definition
 the capability of a study to reject the null hypothesis correctly when there is a true effect or difference in the population
Term
 Retain the Null
Definition
 the actual value does not meet or beat the critical value
Term
 Beta
Definition
 the symbol for the probability of a Type II Error
Term
 Independent Two-Sample Design
Definition
 comparing one group of subjects directly against another group of subjects to determine if the characteristic that differentiates the groups makes a difference
Term
 Random Selection
Definition
 a technique for picking subjects where each one has an equal chance of being selected
Term
 Repeated Measures Two-Sample Design
Definition
 testing the same group of subjects twice, once under each condition of the experiment
Term
 Standard Error of the Difference
Definition
 the standard error component in the two-sample design
Term
 Placebo
Definition
 an experimental treatment that looks real but in actuality is not
Term
 Control Group
Definition
 the group of subjects who do not get the true experimental treatment
Term
 Experimental Group
Definition
 the group of subjects who get the real treatment in a study
Term
 Analysis of Variance
Definition
 an experimental design that allows you to include three or more samples in the same experiment
Term
 Sum-of-Squares Within
Definition
 a measure of how dispersed the scores are inside the samples or conditions of an experiment
Term
 Sum-of-Squares Between
Definition
 a measure of how much dispersion there is in the means of the samples or conditions of an experiment
Term
 Grand Mean
Definition
 the overall mean of the scores in an experiment collapsed across the various samples or conditions being tested
Term
 Post-Hoc Tests
Definition
 procedures that help identify which samples in a research study come from and represent a different population than the other samples
Term
 Parametric Tests
Definition
 statistical procedures that focus on estimation of one or more population parameters and requires interval or ratio data
Term
 Non-Parametric Tests
Definition
 statistical test designed to handle frequency (i.e.,nominal) data, which typically involve few if any assumptions
Term
 Chi-Square Procedure
Definition
 most common nonparametric test
Term
 Expected Frequency
Definition
 the number of observations tat would occur in a given category if there were absolutely no differences among the categories
Term
 Goodness-of-Fit Test
Definition
 a procedure which compares observed results against a set of expected results to determine if they represent the same or different populations
Term
 Correlation Coefficient
Definition
 a mathematical index that indicates the strength and direction of the association between two variables
Term
 Predictor Variable
Definition
 the variable that is being used to predict the other variable in a correlation analysis
Term
 Criterion Variable
Definition
 the variable that is being predicted by the other variable in a correlation analysis
Term
 Cross-Product
Definition
 the deviation score for the first variable multiplied by the deviation score for the second variable
Term
 Covariation
Definition
 the degree to which scores on one variable follow a consistent pattern in relation to the other variable, either positive or negative
Term
 Meta-Analysis
Definition
 an inferential technique that allows you to derive characteristics of a population by mathematically combining results from a group of existing studies
Term
 Effect Size
Definition
 a test statistic used in meta-analysis. denoted as d, it reflects the degree to which the mean of one group is different from the mean of another group (e.g., experimental versus control)
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