REVIEWER

• Statistics


  Quantitative measurements of samples
• Statistical inference


  Making a statement about the population and all its samples based on what we see in the samples we have
• Key elements in statistical inference

  • Population
  • Sample
  • Randomly selected
• Variability


  The amount of change or fluctuation we see in something
• Null Hypothesis (Ho)


  A statement that the performance of treatment groups is so similar that the groups must belong to the same populations' a way of saying that the experimental manipulation had no important effect
• Alternative hypothesis (H1)


  There is no way to directly test the states that the data came from different populations
• Directional Hypothesis (One-Tailed)


  A statement that predicts the exact patterns of results that will be observed, such as which treatment group will perform best
• Normal Curve


  A symmetrical, bell-shaped curve. Many of the scores represented by this distribution fall close to the center
• Significance level (alpha level)

  A criterion for deciding whether to reject the null hypothesis or not. P < 05 (read "p less than .05")
• Experimental Errors


  Variations in subjects' scores produced by uncontrolled extraneous variables in the experimental procedure, data might not be a true reflection of the independent variable's impact
• Type 1 Error (False Positive)

  An error made by rejecting the null hypothesis even though it is really true; stating that an effect exists when it really does not
• Type 2 Error (False Negative)


  An error made by failing to reject the null hypothesis even though it is really true; failing to detect a treatment effect
• Effect size


  A statistical estimate of the size or magnitude of a treatment effect
• Confidence intervals


  A range of values that we feel confident will include the population mean (the true mean)
• Two-tailed test


  A statistical procedure used when a non- directional prediction has been made, the critical region of the distribution of the test statistic is divided over both tails of the distribution
• Non-directional hypothesis


  A statement that predicts a difference between treatment groups without predicting the exact pattern of results
• One-tailed test


  Statistical procedure used when a directional prediction has been made, the critical region of the distribution of the test statistic is measured in just one tail of the distribution
• Inferential statistics


  Statistics that can be used as indicators of what is going on in the population. They are also called test statistics because they can be used to evaluate results
• Test statistic


  A numerical summary of what is going on in our data
• Raw Data


  Data recorded an an experiment is run; the responses of individual subjects
• Summary Data


  Descriptive statistics computed from the raw of an experiment, including the measures of central tendency and variability
• Descriptive statistics


  The standard procedures used to summarize and describe data quickly and clearly; summary statistics reported for an experiment, including mean, range and standard deviation
• Measure of Central Tendency


  Summary statistics that describe what is typical of a distribution of scores; include mean, median and mode
• Mode


  The most frequently occurring score in a distribution; a measure of central tendency
• Mean


  An arithmetical average computed by dividing the sum of a group of scores by the total number of scores, a measure of central tendency
• Median


  If the scores in a distribution are listed in order from smallest to largest, the median is the midpoint of the list
• Variability


  Fluctuation in data; can be defined numerically as the range, variance, or standard deviation
• Range


  The difference between the largest and smallest scores in a set of data; a rough indication of the amount of variability in the data
• Variance

  The average squared deviation of scored from their mean; a more precise measure of variability than the range
• Standard Deviation


  A measure of the amount of variation or dispersion of a set of values
• Independent Variable


  An experiment's independent variable (IV) is the dimension that the experimenter intentionally manipulates
• Dependent Variable


  The response measure of an experiment that is dependent on the subject
• Hess (1975) tested the hypothesis: Large pupils make people more attractive
• Schachter's hypothesis states a potential relationship between two variables—anxiety and affiliation
• Operational definition


  Specifies the precise meaning of a variable within an experiment: It defines a variable in terms of observable operations, procedures, and measurements
• Experimental operational definitions


  Explain the precise meaning of the independent variables; these definitions describe exactly what was done to create the various treatment conditions of the experiment
• Measured operational definitions


  Describe exactly what procedures we follow to assess the impact of different treatment conditions
• Hypothetical constructs or concepts


  Unseen processes postulated to explain behavior
• Reliability


  Consistency and dependability. Good operational definitions are reliable
• Interrater Reliability


  One way to assess reliability of measurement procedures is to have different observers take measurements of the same responses