Exam 3 Research Methods 8,9,10,11,12

Descriptive Stats

Procedures used to summarize a set of data

Inferential Stats

Procedures used to analyze data after an experiment is completed in order to determine whether the IV has a significant effect.

Measurement

The assignment of symbols to events according to a set of rules (professors grading criteria)

Scale Of Measurement

Particular set of rules used in assigning a symbol to the event in question

Nominal Scale

A scale of measurement in which events are assignments to categories (questionnaires “agree”, “disagree”, “undecided”) Least amount of info

Ordinal Scale

A scale of measurement that permits events to be rank ordered

Interval Scale

A scale of measurement that permits rank ordering of events with the assumption of equal intervals between adjacent events ( temp on a thermometer)

Ratio Scale

A scale of measurement that permits rank ordering of events with the assumptions of equal intervals between adjacent events and a true zero point ( intensity of sound or light) “twice as much” and “half as much”

Mode

The score in a distribution that occurs most often ( only measure of central tendency that can be used nominal data)

Median

The number that divides a distribution in half ( can be calculated for ordinal,interval, or ratio data)

Mean

Mathematical average of a set of numbers, found by adding all of the scores and then dividing by the number of scores

Null Hypothesis

A hypothesis that states all differences between group are due to chance ( not the operation of the IV) Reject when t-value is equal or greater than the t-table No effect

t- Test

An inferential stat test used to evaluate the differences between the two means

Degrees of Freedom

The ability of a number in a specified set to assume any value

Type I 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 or size of the experimental treatment

Replication

An additional scientific study that is conducted in exactly the same manner as the original research project.

Demand Characteristics

Features of the experiment that inadvertently lead the participants to respond in a particular manner

Cross-Cultural Psychology

Branch of psychology whose goal is to determine the universality of research results

Internal Validity

A type of evaluation of your experiment; it asks if whether your IV is the only possible explanation for the results shown in your DV ( The most important property of any experiment)

Threats to Internal Validity

• History

• Maturation

• Testing

• Instrumentation (Instrument Decay)

• Stat. Regression

• Selection

• Mortality

• Interactions with Selection

• Diffusion or Imitation of a Treatment

Maturation (Threat to Internal Validty)

A threat to internal validity ; refers to changes in participants that occur over time during an experiment; could include actual physical maturation or tiredness,boredom,hunger, etc.

Testing

A threat to internal validity that occurs because measuring the DV causes a change a in the DV ex-( testing participants more than once)

Instrumentation (Instrument Decay)

A threat to internal validity that occurs if equipment or human measuring the DV changes the measuring criterion over time

Stat. Regression

A threat to internal validity that occurs when low scores improve or high scores fall on a second administration of a test soley as a result of stat. reasons

Selection

A threat to internal validity that can occur if participants are selected in a way that the groups are unequal before the experiment; the researcher cannot then be certain that the IV caused any difference observed after the experiment.

Mortality

A threat to internal validity that can occur if experimental participants from different groups drop out the experiment at different times.

Interactions with Selection

Threats to internal validity that can occur if there are systematic differences between or among selected treatment groups based on maturation, history, or instrumentation

Diffusion or imitation of a treatment

A threat to internal validity that can occur if one treatment group becomes familiar with the treatment of another group and copies treatment.

External Validity

A type of evaluation of an experiment; do the experimental results apply to pops and situations that are different from those of the experiment?

Generalization

Applying results from experiment to a different situation or pop.

Population Generalization

Applying results from experiment to a group of participants that is different and more encompassing than those used in the original experiment.

Environmental Generalization

Applying results from experiment to a situation / environment that differs from the original experiment.

Temporal Generalization

Applying results from the experiment to a time that is different from the time when the original experiment was conducted (ex-seasonal depression)

Introduction of Testing and Treatment

A threat to external validity that occurs when a pretest sensitizes participants to the treatment yet to come

Interaction of Selection and Treatment

A threat to external validity that can occur when a treatment effect is found only for a specific sample of participants.

Reactive Arrangements

A threat to external validity caused by an experimental situation that alters participants behavior regardless of the IV involved (ex- Hawthorne Studies)

Demand Characteristics

( Increased by reactive arrangements creating further difficulties with generalization) Features of the experiment that inadvertently lead to participants to respond in a particular manner.

Mutiple- Treatment Inference

A threat to external validity that occurs when a set of findings results only when participants experience multiple treatments in the same experiment

The Infamous White Rat

The most common used animal participant in a study that became popular in the 1930’s

Comparative Psychology

The study of behavior in different species, including humans

The Ubiquitous College Student

Using such as a participant is connivence sampling

The “Opposite” or “Weaker” or “Inferior” or “Second Sex”

Sexism in early psychology and how overwhelming majority of women studying psychology. Should not use 1 sex to generalize findings.

Even the Rats and Students were White

• Fracis Cecil Sumner- first Black man to get a Ph.D. in psychology

• Ruth Winifred Howard- first Black woman to a get a Ph.D psychology

Even the Rats, Students, Women, and Minorities were American

• Cross- Cultural research

• Ethnocentrism

Replication with Extension

An experiment that seeks to confirm (replicate) previous findings but does so in a different setting or with different participants or under different conditions.

History (Threat to Internal Validity)

A significant event (other than the IV) occurs
between DV measurements.
– Measure participants more than once
– Administering the IV between two DV - Pretest and Posttest
– Interested in how participants react to the IV over time.

Experimental Design

General plan for selecting participants, assigning participants to experimental conditions, controlling EV’s and gathering data

Principle of Parsimony

Belief that explanations of phenoma and events should be remain simple until the simple explanations are no longer valid

Independent Groups

Groups of participants formed by random assignment

Between Subject Comparison

Refers to a contrast between groups of participants who were randomly assigned to groups.

Confounded Experiment

An experiment in which an EV varies systematically with the IV, which makes drawing 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 randomly assigned to treatment conditions 3 ways

1- Matched Pairs

Research participants in a two groups design who are measured and equated on some variable before the experiment (ex-sex)

2- Repeated Design

An experimental procedure which research participants are tested or measured more than once

3- Natural Pairs

Research participants in a two-group design are naturally related in some way bio/social (ex-twin studies)

Within- Subject Comparison

Refers to a contrast between two groups of participants who were assigned to groups through matched pairs, natural pairs, or repeated measures.

Between Group 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 IV, such as individual differences, measurement errors, and EV’s

Degrees Of Freedom

The ability of a number in a specified set to ensure any value

True Experiment

An experiment in which the experimenter directly manipulates the IV

Ex Post Facto Research

A research approach in which the experimenter cannot directly manipulate the IV but can only classify, categorize, or measure the IV b/c it’s predetermined in participants (ex-sex)

Homogeneity of Variance

The assumption that the variances are equal for the two or more groups you plan to compare statistically

Heterogeneity of Variance

Occurs when we do not have homogeneity of variance; means that our two or more groups are not equalivant

Robust

Refers to a stastical test that can tolerate violation of it’s assumptions (homogeneity of variances, and still yield valid results)

Positive Correlation

As scores on one variable increase, scores on the second variable increase

Negative Correlation

As scores on one variable increase, scores on the second variable decrease

One Tail T-test

Evaluates the probality of only one type of outcome (based on directional hypothesis-5%)

Two- Tailed T-test

Evaluates the probality of both possible outcomes (based on non-directional hypothesis 2.5%)

Alpha

The cutoff you decide on to judge significance (ex- Alpha of 1 level of confidence 95%=0.05 or that 5 times out of 100 results will occur due to chance)

Cohens d and P-value

P-values show whether an effect exists are the results of stat significance, while Cohens d Quantifies the size of that effect . What are the practical relevance of the findings

Cohens D small effect

d= 0.2

Cohens D Medium effect

d=0.5

Cohens D Large effect

D=0.8

Correlated Groups

Groups of participants formed by matching pairs, or repeated measures

Matched Variable

Matched pairs not appropriate for multiple group design because there must be at least 3 groups- Must use matched sets ( A potential EV on which we measure our research participants and from we form sets of participants who are equal on the variable (ex- participant sex as EV, to control four participants matched on sex,each randomly assigned to four groups, which makes distribution of sex uniform)

Natural Sets

Same as natural pairs, but must include more than two research participants (ex-littermates-shared heredity makes them more similar than randomly selected animals)

Placebo Effect

An experimental effect caused by expectation or suggestion rather than the IV

One Way ANOVA

A stats test used to analyze data from an experimental design with one IV that has three or more groups (levels)

Completely Randomized ANOVA

This one-way ANOVA uses independent groups of participants

Repeated Measures ANOVA

(Used for matched sets, natural sets, or repeated measures) This one-way ANOVA uses correlated group participants

Operational Definition

Defining the IV, and EV in terms of the operations needed to produce them

Between Groups Variability

Variability in DV scores that is due to effects of the DV

Within-Groups/Error Variability

Variability in the DV scores is due to factors others than IV, such as individual differences, measurement errors, and extraneous variation

Source Table

A table that contains the results of ANOVA. Source 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” varibaility for each source; computed by dividing each sources sum of squares by it’s dfs

Variance

A single number that represents the total amount of variation in a distrubution; also the square of SD q ²

Post- Hoc Comparison

Stat. Comparison made between group means after finding a significant F-ratio

Asymptotic

Refers to tails of distribution that approach the baseline but never touch the baseline

DF for Correlated

(n-1)= df

DF for Independent

(n-1)(n-1)=df

Factorial Design

An experimental design with more than one IV

Main Effect

Refers to sole effect of one IV in a factorial design (ex- solitary effect of customer hearing and solitary effect of salesclerk sex)

Interaction

The joint stimulus effect on the DV of more than one IV, the effects of one IV depend on a particular level of another IV (ex- salesclerk sex and wait time on customer based on disability/ no disability)

Mixed Assignment

A factorial design that has a mixture of independent groups for one IV and correlated groups for another IV. In larger factorial designs at least one IV has an independent group and at least one has a correlated group

3-Way Design

(2×2×2)=8 groups of a factorial design with the 3 IV’s. (determination of how many groups is on whether we choose independent or repeated)

Treatment Variability

Variability in DV scores due to the effects of IV (aka btwn-groups variability) (with factorial designs sources of treatment of variability increase)

Synergistic Effects

Dramatic consequences that occur when you combine 2 or more substances, conditions, or organisms. The effects are greater (or less) than what is individually possible (ex-drinking and driving)