a single number that represents the total amount of variation in a distribution; also the square of the standard deviation.
Standard deviation
scuare root of the variance
Normal distribution
a symmetrical, bell- shaped distribution having half the scores above the mean and half the scores below the mean.
The number that occurs most frequently
mode
A_______ presents data in terms of frequencies per category.
histogram
The ______ is a single number that represent she total amount of variability in a distribution.
Variance
Correlation Coefficient
A single number representing the degree of relation between two variables.
Null hypothesis
a hypothesis that says that all differences between groups are due to chance.
t test
the inferential statistical test used to evaluate the difference between two means.
Degrees of freedom
the ability of a number in a specified set to assume andy value
df =
(Na-1)+(Nb-1)
If students wear dressy clothes to the shopping mall, then the time it takes a salesperson to offer to serve them will be shorter then the latency to service for students dressed in sloppy.
One-tail, directional hypothesis
One tail
evaluates the probability of only one possible outcome
directional hypothesis
An experimental hypothesis my be incorrectly REJECTED.
Type II error
An experimental hypothesis my be incorrectly ACCEPTED.
Type I error
Type 1 error
Accepting the experimental hypothesis when the null hypothesis is true
Type II error\
Accepting the null hypothesis when the experimental hypothesis is true.
Effect size
The magnitude of size of the experimental treatment.
The one-tail test of significance is associated with a
directional hypothesis
The Type I error
is under the direct control of the experimenter
If yo could compare all men and women in the world, you would grind that men are significantly more aggression between men and women. You have made a
type II error
Experimental design
the general plan for selection plan for selection participants, assigning participants to experimental conditions, controlling extraneous variables, and gathering data.
Principle of parisimony
the belief that explanations of phenomena and events should remain simple until the simple explanations are no longer valid.
Exp. Don't needlessly complicate the question that you are asking.
Two group design in the most parsimonious
The least amount of groups in a simple single IV experiment?
two
Control Group and Experimental Group
Independent Variable (IV)
A stimulus or aspect of the environment that the experimenter directly manipulates to determine its influences on behavior.
Dependent Variable
A response or behavior that the experimenter measures. Changes in DV should be caused by manipulation of the Independent variable.
Extraneous Variables
Uncontrolled variables that may unintentionally influences the dependent variable (DV) and thus invalidate an experiment.
Levels
Differing amounts or types of an IV used in an experiment (also known as treatment conditions)
If the probability of the result occurring by chance is less then .05 what can be concluded?
the two groups differ significantly
Experimental group
in two-group design, the group of participants that does not receive the IV.
Random Assignment
a method of assigning research participants of groups that each participants to groups so that each participants has an equal chance of being in any group.
Random Selection
a control techniques that ensures that each member of the the population has an equal chance of being chosen for an experiment.
Independent Groups
Groups of participants formed by random assignment.
Between-Subjects comparison
refers to a contrast between groups of participants how were randomly.
Confounded Experiment
and experiment in which an extraneous variable varies systematically with the IV, which makes drawing a cause-and-effect relation impossible.
Correlated Assignment
A method of assigning research participants to groups so that there is a relationship between small numbers of participants; these small groups are then randomly assigned to treatment conditions
Matched Pairs
Research participants in two-group design who are measured and equated on some variable before experiment.
Repeated measures
an experimental procedures in which research participants are tested or measured more than once.
Natural Pairs
research participants in two-group design who are naturally related in some way
Within-subjects comparison
refers to a contras between groups of participants who were assigned to groups through matched pairs natural pairs, natural pairs, or repeated measures
The differing amounts of you IV are known as the _____ of the IV.
levels
Flipping a coin is an example of what type of assignment
Random Assignment
Brother and sister is an example of what type of pair
natural pairs
take the same test each month
repeated measures
two people with the same IQ
matched pairs
Random assignment is more likely to create equal groups when
large samples are involved
Between-groups variability
variability in DV scores that is due to the effects of the IV.
Error Variability
Variability in DV scores that is due to factors other than the IV, such as individual differences, measurement error, and extraneous variation.
aka within-groups variability
Degrees of freedom
the ability of a number in a specified set to assume any value
True Experiment
an experiment in which the experimenter directly manipulates the IV.
Ex Po Facto Research
a research approach in which the experimenter cannot directly manipulate the IV but can only classify, categorize, or measure the IV because it is predetermined in the participants.
Exp. IV = sex male or female
Homogeneity of Variance
the assumption that the variance are equal for the two (or more) groups you plan to compare statistically.
Exp. .222 well above .05 the variability of the scores of the two groups is similar.
Heterogeneity of Variance
Occurs when we do not have homogeneity of variance; this means that our two (or more) groups' variances are not equivalent.
If p value is less then .05 the variability of the scores were not comparable
Robust
refers to the statistical test that can tolerate violation of its assumption and still yield valid results.
Positive Correlation
As scores on on e variable increase, scores on the second variable also increase
Negative correlation
as scores on one variable increase, scores on the second variable decrease.
Compared to the t test for independent groups, the t test for correlated samples________ degrees of freedom.
fewer
If the variability of our two groups is similar, we have______; if the variability of the groups is dissimilar, we have_______.
When we write a report of our experimental results, we explain the results in_______ and _______.
words and numbers
Experimental Design
the general plan for selecting participants, assigning participants to experimental conditions, controlling extraneous variables, and gathering data.
Independent Variables (IV)
a stimulus or aspect of the environment that the experimenter directly manipulates to determine its influence on behavior.
Principle of Parisimony
the belief that explanations of phenomena and events should remain simple until the simple explanations are no longer valid.
Levels
differing amounts or types of an IV used in an experiment.
(also known as treatment conditions)
Treatment Groups
groups of participants that receive the IV
Independent Groups
groups of participants formed by random assignment
Correlated Groups
Groups of participant formed by matching, natural pairs, or repeated measures.
Random Assignment
a method of assigning research participants to groups so that each participant has an equal chance of being in any group
Control Procedure
one of several steps experimenters take to ensure that potential extraneous variables are controlled, including random assignment matching, and so on
Confounded Experiment
An experiment in which an extraneous variable varies systematically with the IV, which makes drawing a cause-and-effect relation impossible.
Matching Variables
a potential extraneous variable on which we measured our research participants and from which we form sets of participants who are equal on the variable.
Placebo Effect
an experimental effect caused by expectation or suggestion rather than the IV.
Expo Facto Research
a research approach in which the experimenter cannot directly manipulate the IV but can only classify categorize, or measure the IV because it is predetermined in the participants.
Exp. Sex, male or female
The simplest possible multiple- group would have _____ and _____ treatment groups.
1 and 3
One-way ANOVA
a statistical test used to analyze data from an experimental design with one independent variable that has three or more groups (levels)
Completely Randomized ANOVA
This one-way ANOVA uses independent groups of participants.
Repeated-measures ANOVA
this one-way ANOVA uses correlated groups of participants.
Operational Definition
defining the independent dependent, and extraneous variables in terms of the operations needed to produce them.
Between-groups variability
variability in DV scores that is due to the effects of the IV
Error Variability
variability in DV scores that is due to factors other than the IV, such as individual differences, measurement error and extraneous variation (also known as within-groups variability)
Within-groups Variability
another term for error variability.
Source table
a table that contains the results of ANOVA. Sources refers to the source of the different types of variation
Sum of Squares
the amount of variability in the DV attributable to each source
Mean Square
the "averaged" variability for each source; computed by dividing each source's sum of squares by its degrees of freedom.
Variance
a single number that represents the total amount of variation in distribution; also the square of the standard deviation.
Post hoc comparison
statistical comparison made between group means after fining a significant F ratio.
A zero correlation indicates that changes in one variable are not systematically related to changes in the other variable.
Matthew not passing his test has nothing to do with Paul not passing his test