Psychological Statistics Exam 1 (Chapters 1-4)
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Questions and Answers

What is the definition of statistics?

  • A type of psychological analysis
  • A method for scientific experimentation
  • A means of collecting qualitative data
  • A branch of mathematics used to summarize, analyze, and interpret data (correct)

    • What is the plural form of a single measurement or observation?

    Data

    Define descriptive statistics.

    Procedures used to summarize, organize, and make sense of a set of scores or observations.

    What is inferential statistics used for?

    <p>To infer or generalize observations made with samples to the larger population.</p> Signup and view all the answers

    What is the population in statistical terms?

    <p>The set of all individuals, items, or data of interest.</p> Signup and view all the answers

    What is a population parameter?

    <p>A characteristic that describes a population.</p> Signup and view all the answers

    What is the definition of a sample?

    <p>A set of individuals, items, or data selected from a population.</p> Signup and view all the answers

    Define a sample statistic.

    <p>A characteristic that describes a sample.</p> Signup and view all the answers

    What is science defined as?

    <p>The study of phenomena through strict observation and evaluation</p> Signup and view all the answers

    What are the elements of control in an experiment?

    <p>Manipulation, randomization, and comparison/control.</p> Signup and view all the answers

    What is random assignment?

    <p>A procedure that ensures participants have an equal chance of being assigned to a group.</p> Signup and view all the answers

    What is the independent variable?

    <p>The variable manipulated in an experiment.</p> Signup and view all the answers

    What is the dependent variable?

    <p>The variable that is measured in each group of a study.</p> Signup and view all the answers

    Define operational definition.

    <p>A description of observable events in terms of how they were measured.</p> Signup and view all the answers

    What is a quasi-independent variable?

    <p>A preexisting variable that differentiates groups in a study.</p> Signup and view all the answers

    What are scales of measurement?

    <p>Rules for how the properties of numbers can change with different uses.</p> Signup and view all the answers

    What are nominal scales?

    <p>Measurements where a number is assigned to represent something or someone.</p> Signup and view all the answers

    Define ordinal scales.

    <p>Measurements that convey order or rank.</p> Signup and view all the answers

    What are interval scales?

    <p>Measurements that have no true zero and are distributed in equal units.</p> Signup and view all the answers

    Define true zero.

    <p>A value of 0 that truly indicates nothing on a measurement scale.</p> Signup and view all the answers

    What is a continuous variable?

    <p>Measured along a continuum at any point beyond the decimal.</p> Signup and view all the answers

    Define discrete variable.

    <p>Measured in whole units or categories not distributed along a continuum.</p> Signup and view all the answers

    What is a quantitative variable?

    <p>Varies by amount and is measured numerically.</p> Signup and view all the answers

    Define qualitative variable.

    <p>Varies by class and is represented as a label.</p> Signup and view all the answers

    What is frequency in statistics?

    <p>The number of times a category or score occurs.</p> Signup and view all the answers

    What is a frequency distribution?

    <p>A summary display for a distribution of data organized by how often scores occur.</p> Signup and view all the answers

    Define simple frequency distribution.

    <p>Displays the frequency of each individual score or category in a distribution.</p> Signup and view all the answers

    What is grouped data?

    <p>Scores distributed into intervals where frequencies fall into given intervals.</p> Signup and view all the answers

    Define interval.

    <p>A discrete range of values within which frequency is contained.</p> Signup and view all the answers

    What is the real range in a data set?

    <p>One more than the difference between the largest and smallest value.</p> Signup and view all the answers

    What is interval width?

    <p>Range of values contained in each interval of a grouped frequency distribution.</p> Signup and view all the answers

    Define interval boundaries.

    <p>Upper and lower limits for each interval in a grouped frequency distribution.</p> Signup and view all the answers

    What is a lower boundary?

    <p>Smallest value in each interval of a frequency distribution.</p> Signup and view all the answers

    What is an upper boundary?

    <p>Largest value in each interval of a frequency distribution.</p> Signup and view all the answers

    Define open interval.

    <p>An interval with no defined upper or lower boundary.</p> Signup and view all the answers

    What are outliers in statistics?

    <p>Extreme scores that fall substantially above or below most scores in a dataset.</p> Signup and view all the answers

    What is cumulative frequency distribution?

    <p>A summary display that distributes the sum of frequencies across intervals.</p> Signup and view all the answers

    Define relative frequency distribution.

    <p>Summary display that distributes the proportion of scores in each interval.</p> Signup and view all the answers

    What is a proportion in statistics?

    <p>A part of all measured data; the sum of all proportions equals 1.0.</p> Signup and view all the answers

    Define relative percent distribution.

    <p>Summary display that distributes the percentage of scores in each interval.</p> Signup and view all the answers

    What is cumulative relative frequency distribution?

    <p>Summary display that distributes the sum of relative frequencies across intervals.</p> Signup and view all the answers

    Define cumulative percent distribution.

    <p>Summary display that distributes the sum of relative percents across intervals.</p> Signup and view all the answers

    What is a percentile point?

    <p>Value of a score below which a specified percentage of scores fall.</p> Signup and view all the answers

    What is a percentile rank?

    <p>Percentage of scores with values that fall below a specified score.</p> Signup and view all the answers

    Define ungrouped data.

    <p>A set of individual scores or categories where frequency is counted.</p> Signup and view all the answers

    What is a histogram?

    <p>Graphical display summarizing frequency of continuous data in intervals.</p> Signup and view all the answers

    Define frequency polygon.

    <p>A dot-and-line graph used to summarize frequency of continuous data.</p> Signup and view all the answers

    What is an ogive?

    <p>A dot-and-line graph summarizing cumulative percent of continuous data.</p> Signup and view all the answers

    Define bar chart.

    <p>Graphical display summarizing frequency of discrete and categorical data.</p> Signup and view all the answers

    What is a pie chart?

    <p>Graphical display in the shape of a circle summarizing relative percent of data.</p> Signup and view all the answers

    Define sector in a pie chart.

    <p>Particular portion representing the relative percent of a category.</p> Signup and view all the answers

    What is central tendency?

    <p>Statistical measures locating a single representative score.</p> Signup and view all the answers

    Define population size.

    <p>Number of individuals constituting an entire population.</p> Signup and view all the answers

    What is sample size?

    <p>Number of individuals constituting a subset from a larger population.</p> Signup and view all the answers

    Define mean.

    <p>Sum of scores divided by the total number of scores.</p> Signup and view all the answers

    What is population mean?

    <p>Mean for a set of scores in an entire population.</p> Signup and view all the answers

    Define sample mean.

    <p>Mean calculated for a sample.</p> Signup and view all the answers

    What is a weighted mean?

    <p>Combined mean of two or more groups of scores with unequal numbers.</p> Signup and view all the answers

    Define median.

    <p>Middle value in a distribution of data listed in order.</p> Signup and view all the answers

    What is mode?

    <p>Value in a dataset that occurs most frequently.</p> Signup and view all the answers

    Define normal distribution.

    <p>A symmetrical distribution where scores are evenly distributed around the mean.</p> Signup and view all the answers

    What is a skewed distribution?

    <p>A distribution of scores with outliers that fall outside of the main data range.</p> Signup and view all the answers

    Define positively skewed distribution.

    <p>A distribution with outliers that are significantly larger.</p> Signup and view all the answers

    What is a negatively skewed distribution?

    <p>A distribution with outliers that are significantly smaller.</p> Signup and view all the answers

    Define modal distribution.

    <p>A distribution in which one or more scores occur most frequently.</p> Signup and view all the answers

    What is unidimensional or unimodal distribution?

    <p>A distribution where one score occurs most often.</p> Signup and view all the answers

    Define bimodal distribution.

    <p>A distribution where two scores occur most frequently.</p> Signup and view all the answers

    What is multimodal distribution?

    <p>A distribution where more than two scores occur most frequently.</p> Signup and view all the answers

    Define nonmodal distribution.

    <p>A distribution where all scores occur at the same frequency.</p> Signup and view all the answers

    What is variability in statistics?

    <p>A measure of the dispersion of scores in a distribution.</p> Signup and view all the answers

    Define range.

    <p>Difference between the largest and smallest values in a dataset.</p> Signup and view all the answers

    What is interquartile range (IQR)?

    <p>Range of values between the upper and lower quartiles.</p> Signup and view all the answers

    Define semi-interquartile range (SIQR).

    <p>Half the distance between the upper and lower quartiles.</p> Signup and view all the answers

    What is variance?

    <p>A measure of the average squared distance scores deviate from their mean.</p> Signup and view all the answers

    What is population variance?

    <p>A measure of variability for a population's average distance from the mean.</p> Signup and view all the answers

    Define deviation.

    <p>Difference of each score from its mean.</p> Signup and view all the answers

    What is sum of squares (SS)?

    <p>The sum of the squared deviations of scores from their mean.</p> Signup and view all the answers

    What is sample variance?

    <p>A measure of variability for the average squared distance in a sample.</p> Signup and view all the answers

    Define biased estimator.

    <p>A sample statistic that does not equal its respective population parameter.</p> Signup and view all the answers

    What is an unbiased estimator?

    <p>A sample statistic that approximately equals its respective population parameter.</p> Signup and view all the answers

    What are degrees of freedom for sample variance?

    <p>The number of scores in a sample that are free to vary, n-1.</p> Signup and view all the answers

    Define definitional formula for variance.

    <p>A way to calculate variance by summing squared differences from the mean.</p> Signup and view all the answers

    What is computational formula for variance?

    <p>A formula that calculates variance without requiring squared differences.</p> Signup and view all the answers

    Define standard deviation.

    <p>A measure of variability representing average distance from the mean.</p> Signup and view all the answers

    What is population standard deviation?

    <p>A measure of variability for the average distance in a population.</p> Signup and view all the answers

    What is sample standard deviation?

    <p>A measure of variability for the average distance in a sample.</p> Signup and view all the answers

    What does the empirical rule state?

    <p>For normally distributed data, 99.7% lie within three standard deviations.</p> Signup and view all the answers

    What is Chebyshev's theorem?

    <p>Defines the percentage of data within standard deviations from any distribution.</p> Signup and view all the answers

    Study Notes

    Statistics Fundamentals

    • Statistics involves summarizing, analyzing, and interpreting a set of numbers or observations.
    • Data refers to measurements or observations, with a plural form encompassing multiple scores.

    Types of Statistics

    • Descriptive Statistics organize and present data through graphical, tabular, or summary forms.
    • Inferential Statistics enable generalization from sample observations to a broader population.

    Populations and Samples

    • A population includes all individuals or items of interest, while a sample is a subset drawn from that population.
    • Population parameters are characteristics that describe a whole population, whereas sample statistics do so for a sample.

    Research Methodology

    • Science is the systematic study of phenomena through observation and interpretation.
    • The Scientific Method comprises organized techniques for gathering and processing observable data.

    Experimental Design

    • Experiments involve controlling conditions to determine cause-and-effect relationships between variables.
    • Random assignment helps ensure equal chances for participants to be placed in different study groups.

    Variables in Research

    • Independent variables are manipulated, while dependent variables are measured and expected to change due to the independent variable.
    • Operational definitions detail how variables are observed or measured.

    Measurement Scales

    • Scales of Measurement set rules for numerical properties, including nominal (categorizing), ordinal (ordering), and interval (equal units without a true zero).

    Data Distribution and Display

    • Frequency denotes how often scores or categories occur; frequency distributions summarize this occurrence.
    • Histograms and frequency polygons visually display data distributions across intervals.

    Measures of Central Tendency

    • Central Tendency identifies a score that is most descriptive of data: mean (average), median (middle), and mode (most frequent).
    • Normal distribution features symmetric distribution of scores around the mean.

    Variability in Data

    • Variability assesses the spread of scores, calculated using range, interquartile range, variance, and standard deviation.
    • The range reflects the difference between the highest and lowest values; interquartile range focuses on the middle 50% of data.

    Standard Deviation and Its Importance

    • Standard deviation measures how scores deviate from the mean, indicating data spread.
    • Empirical Rule states that a normal distribution features 68% of data within one standard deviation, 95% within two, and 99.7% within three.

    Estimation in Statistics

    • Biased estimators may not accurately reflect population parameters, while unbiased estimators do on average.
    • Degrees of Freedom (df) indicate the number of scores in a sample free to vary.

    Theorems and Theoretical Applications

    • Chebyshev's Theorem provides a percentage of data within any number of standard deviations, applicable regardless of distribution shape.

    Summary of Key Terms and Definitions

    • Variance quantifies how far data points deviate from the mean.
    • Outliers are extreme values significantly different from the rest of the data.
    • Cumulative frequency distributions sum frequencies across intervals, providing a comprehensive view of data.

    These notes encapsulate the core concepts from Chapters 1-4 of Psychological Statistics, covering definitions, types, and applications in the field.

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    Test your knowledge with flashcards covering key concepts from Psychological Statistics Chapters 1-4. This quiz includes essential terms and definitions that are fundamental to understanding statistical analysis in psychology. Perfect for reviewing before the exam!

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