PSYCH 100B FINAL

Quasi-Experiment

(differs from a true experiment in that the researchers do not have full experimental control.) Then they study participants who are exposed to each level of the independent variable. However, in a quasi-experiment, the researchers might not be able to randomly assign participants to one level or the other; they are assigned by teachers, political regulations, acts of nature—or even by their own choice. Limitations of a Quasi: - Selection, Maturation, History, regression, attrition, testing, and instrumentation effects; observer biases, demand characteristics, and placebo effects—the same kinds of ***internal validity threats that can occur in true experiments.

ALL INTERNAL VALIDITY THREATS

1. Attrition Threat: the tendency of one group to drop out more so than other groups (systematic type of participant) 2. Confound: An alternative explanation for a research finding. 3. Demand Characteristic: A cue to the participants in which participants will shift their behaviors to fit the researcher's/experimenter's goals 4. Design Confound: in which a second variable happens to vary systematically along with the independent variable and therefore is an alternative explanation for the results. 5. History Threat: when it is unclear whether a change in the treatment group is caused by the treatment itself or by an external or historical factor that affects most members of the group. 6. Instrumentation Threat: When a measuring instrument changes over time. 7. Maturation Threat: occurs when an observed change in an experimental group could have emerged more or less spontaneously over time. 8. Order Effects (within-groups design): exposure to one condition changes participant responses to a later condition. 9. Selection-Attrition Threat: participants are likely to drop out of either the treatment group or the comparison group, not both. 10. Selection Threat: occurs in an independent-groups design when the kinds of participants at one level of the independent variable are systematically different from those at the other level.

THREE TYPES OF REPLICATION

1. Direct Replication: to repeat an original study as closely as they can to see whether the effect is the same in the newly collected data 2. Conceptual Replication: conceptual/abstract variables but the procedures for operationalization are different. 3. Replication plus extension: researchers replicate their original and add variables to text additional questions - Might include a new condition; new independent variable

If I'm conducting a study using a mixed subjects, 3 x 3 design, and I want 50 participants per experimental condition, how many total participants do I need?

3x3--> 50*3=150 participants

Categorical/Nominal Variable

A nominal variable is another name for a categorical variable. Nominal variables have two or more categories without having any kind of natural order. they are variables with no numeric value, such as occupation or political party affiliation STAT ANALYSIS GRAPH: BAR GRAPH

What's the difference between a true experiment and a quasi experiment?

A quasi-experiment differs from a true experiment in that the researchers do not have full experimental control. They start by selecting an independent variable and a dependent variable. However, in a quasi-experiment, the researchers might not be able to randomly assign participants to one level or the other; they are assigned by teachers, political regulations, acts of nature—or even by their own choice

interrupted time-series design,

A quasi-experiment in which participants are measured repeatedly on a dependent variable before, during, and after the "interruption" caused by some event

nonequivalent control group interrupted time-series design

A quasi-experiment with two or more groups in which participants have not been randomly assigned to groups; participants are measured repeatedly on a dependent variable before, during, and after the "interruption" caused by some event, and the presence or timing of the interrupting event differs among the groups.

"Participants prefer Scorsese in the late period over Allen in the late period"

A simple effect of direct at one level of period simple effect is the effect of one independent variable within one level of a second independent variable.

multiple-baseline design

A small-N design in which researchers stagger their introduction of an intervention across a variety of contexts, times, or situations

reversal design,

A small-N design in which a researcher observes a problem behavior both before and during treatment, and then discontinues the treatment for a while to see if the problem behavior returns.

stable-baseline design

A small-N design in which a researcher observes behavior for an extended baseline period before beginning a treatment or other intervention, and continues observing behavior after the intervention.

Small-N Design

A study in which researchers gather information from just a few cases.

Correlational Study vs. Experimental Study

An experiment isolates and manipulates the independent variable to observe its effect on the dependent variable, and controls the environment in order that extraneous variables may be eliminated. Experiments establish cause and effect. A correlation identifies variables and looks for a relationship between them.

Wait-List Design

An experimental design for studying a therapeutic treatment, in which researchers randomly assign some participants to receive the therapy under investigation immediately, and others to receive it after a time delay.

Nonequivalent Control Group Design (independent group design)

An independent groups quasi-experiment that has at least one treatment group and one comparison group, but participants have not*** been randomly assigned*** to the two groups.

nonequivalent control group pretest/posttest design, (independent group design)

An independent-groups quasi-experiment that has at least one treatment group and one comparison group, in which participants have not been randomly assigned to the two groups, and in which at least one pretest and one posttest are administered.

Case Study Archival Research Correlational Research

Case studies are a prospective or retrospective deep dive into a single case, used a lot in business, education, and perhaps also law, medicine (more often retrospective) or other fields. Experimental research involves comparisons of variables under manipulated conditions.

Confounding, Counterbalance, Cohort Variable

Confound: Many possible explanations for an outcome. Occurs when a researcher does not control some extraneous variables that may influence the results Counterbalance: In a repeated-measures experiment, presenting the levels of the independent variable (IV) to participants in different sequences to control for order effects. Cohort: a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation

Situation Noise

External Distractions causes variability within groups and obscure true groups difference --> Causes unsystematic variability: variability within individuals and/or groups of individuals. This variability is essentially random; some individuals change in one direction, others in an opposite direction, and some do not change at all.

ANOVA: F TEST

F test helps determine whether the differences among the three groups are statistically significant. Just as with the t test, two sources of variability will influence the distances between these three groups. One is the variability between the three means themselves. The other is how much variability there is within each of the groups. when the F ratio is large, it means there is more variability between the groups than there is within the groups: The groups' scores are far apart and do not overlap much. When the F ratio is small, it means there is about the same (or even less) variability between the groups than there is within the groups; the groups overlap more.

Data Fabrication vs. Data Falsification

Fabrication: instead of recording what really happened in a study, researchers invent DATA that fits their hypothesis --->MAKING UP DATA Falsification: when a researcher influences a study's results by selectively deleting observations from data set or influencing subjects ---> DELETING DATA

What does the following statement describe? "of the participants who ate at Domino's, vegetarians liked the pizza more than carnivore's" IV1: Eating Habit IV2: Restaurant

Simple effect of eating habit simple effect is the effect of one independent variable within one level of a second independent variable.

Construct vs. Internal Validity

Internal Validity: One of three criteria for establishing a causal claim; a study's ability to rule out alternative explanations for a causal relationship between two variables. Also called third-variable criterion. Construct Validity: An indication of how well a variable was measured or manipulated in a study.

What does the following statement describe? "participants preferred Domino's over Pizza Hut, regardless of whether they were vegetarian or carnivore" IV1: Eating Habit IV2: Restaurant

Main effect of restaurant (domino's)

Pretest/Posttest vs. Interruption Exp. Design

Pretest/Posttest Exp. Design: An experiment using an independent-groups design in which participants are tested on the key dependent variable twice: once before and once after exposure to the independent variable.

Regression Threat vs. Regression to the Mean

Regression Threat: A threat to internal validity related to regression to the mean, a phenomenon in which any extreme finding is likely to be closer to its own typical, or mean, level the next time it is measured (with or without the experimental treatment or intervention). Regression to the mean: A phenomenon in which an extreme finding is likely to be closer to its own typical, or mean, level the next time it is measured, because the same combination of chance factors that made the finding extreme are not present the second time.

Insensitive Measure

Researchers failed to use an operationalization of the dependent variable (DV) with enough sensitivity

four types of statistical testing

T-TEST: The t test for independent groups is the appropriate test for evaluating whether two group means are significantly different. F-TEST: When a study compares two or more groups to each other obtained from an analysis of variance(ANOVA) tests of the significance of a correlation; tests of the significance of beta.

What are testing threats (threat to internal validity) and how can we prevent them?

Testing threats: refers to a change in the participants as a result of taking a test (dependent measure) more than once. Soln: To avoid testing threats, researchers might abandon a pretest altogether and use a posttest-only design. If they do use a pretest, they might opt to use alternative forms of the test for the two measurements. A comparison group can also help. If the comparison group takes the same pretest and posttest but the treatment group shows an even larger change, testing threats can be ruled out

Ch. 8: 4. Darrin reads a story reporting that students at private colleges get higher GPAs than those at public colleges. He wonders if this means going to a private college causes you to have a higher GPA; if so, he'll go to a private college! Applying the three causal criteria, Darrin knows there is covariance here. He also knows there is temporal precedence because you choose a college first, and then you get your GPA. Which of the following questions would help Darrin ask about the third criterion, internal validity? a. Could there be restriction of range? b. Is the link between private college and high grades the same for both men and women? c. How did they decide what qualifies a college as private or public? d. Is there some other reason these two are related? Maybe better students are more likely to go to private colleges, and they are also going to get better grades.

Third Variable Criterion: When we can come up with an alternative explanation for the association between two variables, that alternative is some lurking third variable. d. Is there some other reason these two are related? Maybe better students are more likely to go to private colleges, and they are also going to get better grades.

What are history threats (to internal validity) and how can we prevent them?

This results from a historical or external factor that systematically* (according to a fixed plan or system; methodically.) affects most members of the treatment group at the same time as the treatment itself, making it unclear whether the change is caused by the treatment received. Soln: Comparison groups can help prevent history threats because both the treatment group and the control group should experience the external factor. -- therefore the threat is controlled.

Parametric vs. Nonparametic

a branch of statistics which assumes that sample data comes from a population that can be adequately modelled by a probability distribution that has a fixed set of parameters.

What are Maturation Threats (to internal validity) and how can you prevent them?

a change in participant behavior that emerges more or less spontaneously over time. People adapt to changed environments; children get better at walking and talking; plants grow taller—but not because of any outside intervention. It just happens. Soln: Changing your experiment to a true experiment such as pretest/pottest design which have at least two groups not one. -- this way we would have a comparison group

Ex Post Facto Design

a quasi-experimental study examining how an independent variable, present prior to the study in the participants, affects a dependent variable. A quasi-experimental study simply means participants are not randomly assigned.

Chapter 11 Review Questions Dr. Weber conducted a long-term study in which people were tested on happiness, asked to make two new friends, and then tested on happiness 1 month later. He noticed that six of the most introverted people dropped out by the last session. Therefore, his study might have which of the following internal validity threats? a. Attrition b. Maturation c. Selection d. Regression

a. Attrition--describes the tendency of some people to be more likely to drop out of a study than others.

Ch. 13 4. In the kids' camp study, you could ask: Did the researchers use a reliable and valid test of nonverbal communication skills? You would be asking about which kind of validity? a. Construct validity b. Statistical validity c. Internal validity d. External validity

a. Construct validity

A simple experimental design with two levels of an independent variable cannot: a. Detect a curvilinear relationship between variables b. Detect a monotonic relationship c. Reveal a positive relationship d. Show a negative relationship outcome

a. Detect a curvilinear relationship between variables Curvilinear assn: in which the relationship between two variables is not a straight line; it might be positive up to a point, and then become negative. Monotonic assn: A monotonic relationship is a relationship that does one of the following: (1) as the value of one variable increases, so does the value of the other variable; or (2) as the value of one variable increases, the other variable value decreases.

Ch. 14 4. Which of the following claims is most likely to have been tested in generalization mode? a. Four out of ten teenagers can't identify fake news when they see it. b. Reading stressful news makes adults anxious. c. People who walk faster live longer.

a. Four out of ten teenagers can't identify fake news when they see it.

Ch. 13 5. The researchers found that the ability to read emotions in faces improved significantly in the kids who'd been to the camp, but not in the control kids. Which of the following would be a threat to internal validity in this study? a. If the kids who went to camp were selected for their low levels of emotional communication skills, but the control children were not. b. If the kids in the two groups were representative of children from their local school district. c. If there was no significant difference between the children in the camp group and the control group.

a. If the kids who went to camp were selected for their low levels of emotional communication skills, but the control children were not. Selection Affect: A threat to internal validity that occurs in an independent-groups design when the kinds of participants at one level of the independent variable are systematically different from those at the other level.

Dr. Banks modifies her design and conducts a second study. She uses the same number of dogs and the same design, except now she rewards one group of dogs with miniature hot dogs and another group with pieces of apple. She finds a big difference, with the hot-dogs group learning the command faster. Dr. Banks avoided a null result this time because her design: a. Increased the between-groups variability. b. Decreased the within-groups variability. c. Improved the study's internal validity.

a. Increased the between-groups variability.

Ch. 14 1. If you repeat a study and find the same results as the first time, what can you say about the original study? a. It is replicable. b. It is statistically significant. c. It is valid. d. It is consistent.

a. It is replicable.

Ch. 14 3. ______ a technique in which the researcher mathematically averages the results of all studies that have been completed with the same conceptual variables. a. Meta-analysis b. Correlation c. Literature review d. Analysis of variance

a. Meta-analysis Meta-analysis Correlation Literature review: includes the current knowledge including substantive findings, as well as theoretical and methodological contributions to a particular topic. Analysis of variance (ANOVA)

Ch. 13 1. What is the term for a quasi-experimental design with at least one treatment group and one comparison group, in which the participants are measured once and have not been randomly assigned to the groups? a. Nonequivalent control group design b. Independent-groups design c. Factorial design

a. Nonequivalent control group design Nonequivalent control group design: An independent groups quasi-experiment that has at least one treatment group and one comparison group, but participants have not been randomly assigned to the two groups. Independent-groups design: An experimental design in which different groups of participants are exposed to different levels of the independent variable, such that each participant experiences only one level of the independent variable. Also called between-subjects design or between-groups design.

Ch. 4: 5. What type of research misconduct involves representing the ideas or words of others as one's own? a. Plagiarism b. Obfuscation c. Suppression d. Data falsification

a. Plagiarism

Ch. 4: 6. Which of the following is not one of the Three R's provided by the Guide for the Care and Use of Laboratory Animals? a. Reduction b. Replacement c. Restoration d. Refinement

a. Restoration Replacement: means researchers should find alternatives to animals in research when possible. For example, some studies can use computer simulations instead of animal subjects. Refinement: means researchers must modify experimental procedures and other aspects of animal care to minimize or eliminate animal distress. Reduction: means researchers should adopt experimental designs and procedures that require the fewest animal subjects possible.

Dr. Banks tests to see how many training sessions it takes for dogs to learn to "Sit and stay." She randomly assigns 60 dogs to two reward conditions: one is miniature hot dogs, the other is small pieces of steak. Surprisingly, she finds the dogs in each group learn "Sit and stay" in about the same number of sessions. Given the design of her study, what is the most likely explanation for this null effect? a. The dogs loved both treats (her reward manipulation has a ceiling effect). b. She used too many dogs. c. She didn't use a manipulation check. d. There were too many individual differences among the dogs.

a. The dogs loved both treats (her reward manipulation has a ceiling effect). - Ceiling Effect: an experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the high end of their possible distribution.

Ch. 8: 5. Which of the following sentences describes a moderator for the relationship between risk taking and liking spicy foods? a. There is a positive relationship between liking spicy foods and risk taking for men, but no relationship for women. b. Older adults tend to like spicy foods less than younger adults. c. The relationship between liking spicy foods and risk taking is the same for people in cities and in rural areas.

a. There is a positive relationship between liking spicy foods and risk taking for men, but no relationship for women. When the relationship between two variables changes depending on the level of another variable, that other variable is called a moderator.

Observational research should be used when a. you want to observe some phenomenon in a natural setting b. you want to make causal conclusions about variables that interact in the environment c. you know that your presence will have an effect on subjects' behavior d. you want to be able to generalize your results across time e. you want to have tight control over extraneous variables

a. you want to observe some phenomenon in a natural setting

What does the following describe? The older males with the two types of shorter hair were judged significantly more intelligent than the younger males with the two types of shorter hair, but older males with long hair were judges significantly less intelligent than younger males with long hair

an interaction

Ch. 4: 4. Following a study using deception, how does the researcher attempt to restore an honest relationship with the participant? a. By apologizing to the participant and offering monetary compensation for any discomfort or stress. b. By debriefing each participant in a structured conversation. c. By reassuring the participant that all names and identifiers will be removed from the data. d. By giving each participant a written description of the study's goals and hypotheses, along with references for further reading.

b. By debriefing each participant in a structured conversation.

Ch. 13 6. A psychologist is working with the parents of four children, all of whom exhibit violent behavior toward one another. The parents were instructed to record the number of violent behaviors each child exhibits in the pre-dinner hour for 1 week. The parents then begin using a positive reinforcement technique to shape the behavior of the youngest child, while continuing to record the behavior of all children. The recording continues and the technique is used on one additional child each week. By the end of 6 weeks, there is a significant decrease in violent behaviors for each of the children. What type of design did the psychologist use? a. Stable-baseline design b. Multiple-baseline design c. Reversal design d. Interrupted time-series design

b. Multiple-baseline design Multiple-Baseline Design: A small-N design in which researchers stagger their introduction of an intervention across a variety of contexts, times, or situations. Stable-baseline Design: A small-N design in which a researcher observes behavior for an extended baseline period before beginning a treatment or other intervention, and continues observing behavior after the intervention. Reversal Design: A small-N design in which a researcher observes a problem behavior both before and during treatment, and then discontinues the treatment for a while to see if the problem behavior returns. Interrupted Time Series Design: A quasi-experiment in which participants are measured repeatedly on a dependent variable before, during, and after the "interruption" caused by some event.

A regression threat applies especially: a. When there are two groups in the study: an experimental group and a control group. b. When the researcher recruits a sample whose average is extremely low or high at pretest. c. In a posttest-only design. d. When there is a small sample in the study.

b. When the researcher recruits a sample whose average is extremely low or high at pretest.

Ch. 8: 1. Suppose you hear that conscientious people are more likely to get regular health checkups. Which of the following correlations between conscientiousness and getting checkups would probably support this claim? a. r = .03 b. r = .45 c. r = −.35 d. r = −1.0

b. r = .45 r= effect size that describes the relationship between two or more variables +,-, 0 indicates the direction value indicates the strength if the question is stating that conscientious people are more likely to get regular health checkups --- then this is a positive relationship because as the number of conscious ppl increases so does the number of regular health check-ups

define an interaction

between independent variables indicates that the effect of one independent variable is different at different levels of the other independent variable.

Ch. 14 5. Which of these is a field setting? a. A psychology lab with a hidden camera b. A neuropsychology lab with an MRI machine c. A preschool playground with video cameras d. A biology lab with galvanic skin response detectors

c. A preschool playground with video cameras

Ch. 4: 2. In a study of a new drug for asthma, a researcher finds that the group receiving the drug is doing much better than the control group, whose members are receiving a placebo. Which principle of the Belmont Report requires the researcher to also give the control group the opportunity to receive the new drug? a. Informed consent b. Justice c. Beneficence d. Respect for persons

c. Beneficence 1. Informed consent: The right of research participants to learn about a research project, know its risks and benefits, and decide whether to participate. 2. Principle of Beneficence: An ethical principle from the Belmont Report stating that researchers must take precautions to protect participants from harm and to promote their well-being. 3. Principle of Justice: An ethical principle from the Belmont Report calling for a fair balance between the kinds of people who participate in research and the kinds of people who benefit from it. 4. Principle of Respect for Persons: An ethical principle from the Belmont Report stating that research participants should be treated as autonomous agents and that certain groups deserve special protection.

9. For an analysis of variance, variance is partitioned into two sources. These are ...?

c. Between-groups variability and within-groups variability

Ch. 14 2. When a researcher conducts a replication study in which she has the same variables at an abstract level, but uses different operationalizations of each variable, what type of study is it? a. Direct replication b. Meta-analysis c. Conceptual replication d. Replication-plus-extension

c. Conceptual replication

Ch. 14 6. Which of these statements is true of external validity? a. Psychologists usually strive to generalize to all people. b. For generalization to a population, the larger the sample the better. c. External validity comes from how the sample is obtained, rather than sample size. d. A sample that contains female college students can generalize to all female college students.

c. External validity comes from how the sample is obtained, rather than sample size.

Ch. 13 7. Which of these is not a method for addressing the external validity of the conclusions of a small-N study? a. Triangulate by comparing results with other research. b. Specify a limited population to which to generalize. c. Randomly assign people to the treatment and control conditions. d. Specify that the result applies only to the participant studied.

c. Randomly assign people to the treatment and control conditions. External Validity: An indication of how well the results of a study generalize to, or represent, individuals or contexts besides those in the study itself. Generalizability: The extent to which the subjects in a study represent the populations they are intended to represent; how well the settings in a study represent other settings or contexts.

Ch. 8: 2. Which of these associations will probably be plotted as a bar graph rather than a scatterplot? a. The more conscientious people are, the greater the likelihood they'll get regular health checkups. b. Level of depression is linked to the amount of exercise people get. c. Students at private colleges get higher GPAs than those at public colleges. d. Level of chronic stomach pain in kids is linked to later anxiety as adults.

c. Students at private colleges get higher GPAs than those at public colleges. Bar graph good for categorical/nominal variables and quantitative variable Categorical/Nominal: private vs. public - one or the other Quantitative: GPA

Ch. 13 2. Which of these is not a reason for a researcher to select a quasi-experimental design? a. To enhance external validity. b. To avoid the ethical issues a true experiment would cause. c. To ensure internal validity. d. To take advantage of real-world opportunities to study phenomena and events.

c. To ensure internal validity. Quasi experimental studies have the same internal validity threats as true experiments

Advantages of a small N study

can establish excellent construct and internal validity. They can achieve external validity by replicating the results in other settings, but in applied settings, researchers might prioritize the ability to establish a treatment's effectiveness for a single individual over broad generalizability.

counterbalancing

change up the orders in a within subjects or another receptive experiment design

cross-sectional correlations

cross-sectional correlations; they test to see whether two variables, measured at the same point in time, are correlated

Curvilinear Association

curvilinear association An association between two variables which is not a straight line; instead, as one variable increases, the level of the other variable increases and then decreases (or vice versa).

How is a testing threat to internal validity different from an instrumentation threat? a. A testing threat can be prevented with random assignment; an instrumentation threat cannot. b. A testing threat applies only to within-groups designs; an instrumentation threat applies to any type of study design. c. A testing threat can be prevented with a double-blind study; an instrumentation threat can be prevented with a placebo control. d. A testing threat refers to a change in the participants over time; an instrumentation threat refers to a change in the measuring instrument over time.

d. A testing threat refers to a change in the participants over time; an instrumentation threat refers to a change in the measuring instrument over time.

Ch. 4: 1. Which of the following is not one of the three principles of the Belmont Report? a. Respect for persons b. Justice c. Beneficence d. Fidelity and responsibility

d. Fidelity and responsibility

Ch. 8: 3. A study found that people who like spicy foods are generally risk takers. Which of the following questions interrogates the construct validity of this correlation? a. Is the result statistically significant? b. Did the study use a random sample of people? c. Were there any outliers in the relationship? d. How well did they measure each variable, risk taking and liking spicy foods?

d. How well did they measure each variable, risk taking and liking spicy foods? Construct Validity: An indication of how well a variable was measured or manipulated in a study.

Ch. 4: 3. In order to study a sample of participants from only one ethnic group, researchers must first demonstrate that the problem being studied is especially prevalent in that ethnic group. This is an application of which principle from the Belmont Report? a. Respect for persons b. Beneficence c. Special protection d. Justice

d. Justice Principle of Justice: An ethical principle from the Belmont Report calling for a fair balance between the kinds of people who participate in research and the kinds of people who benefit from it.

Ch. 13 3. Researchers studied preteens at an outdoor education camp that prevented kids from using devices with screens, such as cell phones (Uhls et al.,2014). They predicted the camp would improve children's nonverbal communication skills. One group of sixth graders attended the camp in the spring. They were compared to a group of sixth graders from the same school the following fall, who had not attended the camp. The kids were given a test of how well they could read emotions in faces. The camp group took the emotion test on both Monday and Friday of their camp week; the control group took the emotion test on Monday and Friday of a regular school week. What type of design was this? a. Interrupted time-series design b. Nonequivalent control group interrupted timeseries design c. Nonequivalent control group design d. Nonequivalent control group pretest/posttest design

d. Nonequivalent control group pretest/posttest design

When a study has a large number of participants and a small amount of unsystematic variability (low measurement error, low levels of situation noise), then it has a lot of: a. Internal validity b. Manipulation checks c. Dependent variables d. Power

d. Power Defn: The likelihood that a study will show a statistically significant result when an independent variable truly has an effect in the population; the probability of not making a Type II error.

8. By definition, developmental studies that are conducted longitudinally are ____, whereas cross sectional designs are _____ . a. quasi experimental designs; true experiments b. correlational designs; experimental designs c. between-subjects designs; mixed-subjects designs d. within-subjects designs; between-subjects designs e. both a and d

d. within-subjects designs; between-subjects designs

Descriptive vs. Nondescriptive

descriptive statistics A set of statistics used to organize and summarize the properties of a set of data. The correlation coefficient is considered a descriptive statistic because it describes the direction and strength of a relationship between two numeric variables.

Between Subjects Design

experiment that has two or more groups of subjects each being tested by a different testing factor simultaneously.

Within-Subjects Design

experimental design in which all participants are exposed to every treatment or condition.

extraneous vs. confound variable

extraneous variables, which are any factors that are in the experiment but not being studied, and confounding variables, which are related to the independent variable and affect the dependent variable.

Inferential vs. Noninferential

inferential statistics is the process of using data from a sample whose characteristics are known, to make inferences about some population whose characteristics are often unknown.

Mixed Factorial Design

mixed factorial design involves two or more independent variables, of which at least one is a within-subjects (repeated measures) factor and at least one is a between-groups factor. Example: usually includes a categorical/nominal variable and a

What are instrumentation threats (threats to internal Validity) and how can we prevent them?

occurs when a measuring instrument changes over time. In observational research, the people who are coding behaviors are the measuring instrument, and over a period of time, they might change their standards for judging behavior by becoming more strict or more lenient. Soln: researchers could switch to a posttest-only design, or should take steps to ensure that the pretest and posttest measures are equivalent.

When do replication studies fail?

small samples can accidentally lead to significant findings that can't be replicated - Harking: when a researcher just reports the significant effect, dismissing all variables that do not work --> Hypothesizing after the results are know - P-Hacking: find a value < .05 (this can't be replicated)

Define Main Effect

the effect of each independent variable on the dependent variable