Exam 3 study guide Flashcards
interaction effect
occurs when the effect of one IV depends on the level of another IV
2 types of interaction effects
crossover interaction
- “it depends”
- graph makes a X
spreading interaction
- “only when”
- graph is 75 degree angle facing to the left
how many cells in a 2x2 factorial design
4 cells
participant variables
any demographic characteristics, things the experimenter cannot manipulate
when the graph shows two parallel lines, this represents …
no interaction effect
how do we know there is a large effect shown in a 2x2 factorial
calculate the marginal means for each level of the 2 IV’s (should end up with 4 means) and then compare the marginal means in each IV
interaction effect calculation
- find marginal means (a, b, c, d)
- subtract marginal means in each IV (a-b =x, c-d=y)
- find the difference within IV’s (x-y)
when a study shows both a main effect and an interaction, the interaction is almost always…
more important
you can have ____________ main effects and a ________ interaction effect
non-significant; significant
3 factorial variations
independent-groups factorial design
within-groups factorial designs
mixed factorial designs
independent-groups factorial design
both IVs are studied as independent groups aka between subjects
each cell of the 2x2 has a different group of participants
within-groups factorial design
both IVs are manipulated within groups
only one group of participants in all four cells
mixed factorial designs
one IV is manipulated as independent-groups and the other is manipulated within-groups
2 cells share the same group while the other two cells share a different group
the same group cells are for the independent-groups IV
for a 2x2x2 factorial, there would be …
3 main effects
3 two-way interactions
1 three-way interaction
2 ways to identify factorial designs in empirical journal articles
the method section will describe the study
- __x__x__
the results section will examine whether the main effects and interactions were significant
2 ways to identify factorial designs in popular press articles
look for “it depends” or “only when” to highlight interaction
look for participant variables (age, gender, ethnicity, etc.)
bivariate correlations
associations that involve exactly two variables
ex. level of happiness and days spent on vacation
think quantitative or categorical
cohen’s guidelines
.10 or -.10 = small, or week
.30 or -.30 = medium, or moderate
.50 or -.50 = large, or strong
mean
arthmetic average
t test
a statistic to test the difference between two group averages
do you know how to plot points on a graph then determine if the correlation is positive, negative, or neither?
obviously
construct validity: ask about the construct validity of _____ variable
each
effect size
describes the strength of an association
statistical validity
_____ effect sizes give more accurate predictions
larger
the logic of statistical inference with p < 0.05
< 0.05 what you found in the study isn’t found in the real world, type I error
do you know how to read about significance in journal articles?
yes, table interpretation on slide 32 of bivariate correlational research part 1
outlier
small sample more affected by outliers
changes slope of the line, making correlation appear stronger than it actually is
restriction of range impacts …
strength of correlation
the pearson correlation coefficient is used to measure … and not measure …
the strength of a linear association between two variables
curvilinear associations
4 examples of non-linear relationships
exponentials
free time through life
friendliness of waiters
more money doesn’t equal more happiness at a certain point
3 causal criteria for internal variability (review)
covariance
temporal precedence (directionality problem)
internal validity (third-variable problem)
third variable problem/internal validity
is there a third variable (c) that is associated with variables A and B independently? If so, then we can’t infer causation
identify the third variable:
murder rates and ice cream sales are highly positively correlated
weather, the hotter it is = more people out and about
external validity is more important with _______ claims
frequency
moderating variables
3rd variables are confounds, moderators purposely added to help us understand correlation
ex. extraversion –> happiness, moderating variable: setting
identify the moderator:
“recent research shows that growing up in stressful economic conditions can disrupt brain development, alter behavior and challenge emotions. But for boys, the outcome is worse.”
gender
multivariate designs
such as longitudinal and multiple regression designs, involve more than two measured variables
longitudinal designs
collecting data from some group over long period of time
measuring at multiple time points
cross-sectional correlations
relationship between 2 variables at one time point
can you establish temporal precedence with cross-sectional correlations?
no!
autocorrelations
looking at correlation at each variable of itself across each time
can you establish temporal precedence with autocorrelations?
no!
cross-lag correlations
correlation between one variable and the next time period
what does n.s. stand for, especially when looking at cross-lag correlations?
not significant
what correlation is the closest to establishing temporal precedence?
cross-lag correlations
if both cross-lag correlations are significant, what does this entail?
neutrally reinforcing but don’t know which is causing the other
longitudinal designs can provide SOME evidence for causation by fulfilling three criteria:
covariance
temporal precedence
internal validity
multiple regression
increases the internal validity of study
- help rule out 3rd variable problem
controlling for confounds while predicting one variable w/ another one
3 things to look at to see if regression results indicate if a third variable affects the relationship
criterion variable
predictor variable
use beta to test for third variable
what does testing for beta do?
tell us direction and strength in variables but no cut-offs/guidelines like cohen’s d or r
only used to compare effect sizes
can only compare beta strengths within a …
single regression table
what if beta is not significant?
3rd variable is explaining the link!
can the strongest beta be negative?
yes!
when interpreting a regression table, the answer should have …
the other variables that you controlled for/mentioned in the table
4 regression terms used in popular press articles
“controlled for”
“taking into account”
“correcting for”
“adjusting for”
multiple regression is not a _____ way to rule out all kinds of third variables
foolproof
regression does not establish …
causation!
multiple studies showing same pattern in results = …
increase in internal validity/closer to causal claims
parsimony
study characteristics
the simpler the better
journalists do not always fairly represent ____ and _____
pattern; parsimony
mediator
explaining process in which something happens
2 similarities for mediators and third variables
both involve multivariate research designs
both can be detected using multiple regression
2 differences for mediators and third variables
third variables are external to the bivariate correlation (problematic)
mediators are internal to causal variable (not problematic)
mediators ask “___” because …
why; explains how something causes the other variable to change
moderators ask “__ ____” or “____” because …
for whom or when; change relationship between 2 variables
“Active sex life may lead to improved job satisfaction and engagement in work”
To understand the impact of sex on work, the researchers followed 159 married employees over the course of two weeks, asking them to complete two brief surveys each day. They found that employees who
engaged in sex reported more positive moods the next day, and the elevated mood levels in the morning led to more sustained work engagement and job satisfaction throughout the workday.
what is/are the: study variables, type of study, and mediator
variables: sex life, job satisfaction, engagement in work
correlation study, no manipulation
mediator: elevated mood levels
“People with higher incomes spent less time socializing overall”
“People in households with higher incomes spent significantly less time with relatives and neighbors and significantly more time with friends”
They controlled for age, race, gender, marital status, household size, city size and hours worked to isolate the effect of money on relationships.
what is the technique that this study represents?
multiple regression is seen because they controlled for variables
quasi-experiment
study similar to an experiment except the researchers do not have full experimental control
without random assignment!
need to be cautious when making causal claims
conducted in field/real life settings mostly
4 types of quasi-experimental research designs
nonequivalent control group posttest-only design
nonequivalent control group pretest/posttest design
interrupted time-series design
nonequivalent control group interrupted time-series design
nonequivalent control group posttest-only design
no random assignment
at least 1 treatment and control group
measuring variables only once
nonequivalent control group pretest/posttest design
no random assignment
control group is present
measuring variables twice
interrupted time-series design
no comparison group
measuring before, during, and after interruption/event
ex. 13 reasons why
nonequivalent control group interrupted time-series design
not randomly assigned as groups already exist
with comparison group
8 threats to internal validity in quasi-experiments (review from ch.11)
maturation threat
history threat
regression to the mean
attrition threat
testing and instrumentation threats
selection effects
design confounds
observer bias, demand characteristics, and placebo effects
4 strengths of quasi-experiments
real-world opportunities
external validity
ethics
construct validity and statistical validity in quasi-experiments
A series of studies has been conducted to figure out if children in preschool benefit more from free play (such as with a water table) or direct instruction in reading or math. One study found that early academic instruction might worsen academic performance. Rebecca A. Marcon, a psychology professor at the University of North Florida, studied 343 children who had attended either a preschool class that was “academically oriented” or one that encouraged “play-oriented” learning. She assessed the students’ performance several years later, in fourth grade, and found that by
the end of the fourth grade those who had received more direct instruction earned significantly lower grades than those who had been allowed more opportunities to learn through play.
What kind of quasi-experimental design does this appear to be?
A. nonequivalent control group design (posttest-only)
B. nonequivalent control group design (pretest/posttest)
C. interrupted time-series design
D. nonequivalent control group interrupted time-series
design
A
Bushman and Anderson (2009) conducted a study in a movie theater. They used patrons who had already decided to attend one of two movies—a violent movie or a nonviolent movie. Either before or after the movie, they staged little accidents in the lobby of the theater (in which a confederate dropped her crutches and was trying to pick them back up) and measured how many people helped. People at the two movies were equally likely to help before the movie, but afterward, the people who’d seen a violent movie were slower to come to her aid.
What kind of quasi-experimental design does this
appear to be?
A. nonequivalent control group design (posttest-only)
B. nonequivalent control group design (pretest/posttest)
C. interrupted time-series design
D. nonequivalent control group interrupted time-series
design
B
for large vs. small N designs, participants are …
large - grouped
small - treated separately
for large vs. small N designs, data is represented …
large - as group averages
small - with each individual
for large vs. small N designs, the results are supposed to represent …
large - enable group averages to be estimated more precisely
small - careful designs enable us to compare each individual during treatment periods and control periods
for large vs. small N designs, what type of research are they classified as?
large - basic and applied research
small - often used in therapeutic settings to confirm that a treatment works for an individual
research on human memory with Henry Molaison is an example of ____-N design
small; studying special cases!
disadvantages of small-n studies
external and internal validity (internal b/c no random assignment/possible 3rd variable issue)
stable-baseline designs
observe behavior for baseline
see if behavior changes after intervention
con: can’t rule out 3rd variable issue
multiple-baseline designs
staggering intro of intervention across difference individuals
reversal designs
stop treatment to see if behavior reverts back
for small-n designs, internal validity can be very high if…
the study is carefully designed
for small-n designs, external validity can be problematic depending on…
the goals of the study
for small-n designs, construct validity can be very high if…
definitions and observations are precise
for small-n designs, statistical validity is …
not always relevant
direct replication
repeating original study as closely as you can
con: if there is a problem in the original study, there will be for yours as well
conceptual replication
not directly repeating, exploring same topic with different method/procedure
replication-plus-extension
repeating original study as closely as possible while adding new variables to test new questions
what is the difference between generalization mode and theory-testing mode
when external validity is important
replication crisis (2 examples)
Open Science Collaboration (OSC)
- replicated studies once
- low success rate, replicated more social not cognitive studies more successfully
Many Labs Project (MLP)
- replicated each study more than once
- higher success rate!
selective publication
studies with significant findings more likely to be published than studies without significant findings
problems with original study/questionable research practice
sample size
- small n’s more likely to be influenced by outliers
HARKing (hypothesizing after the results are known)
- run analysis and then create hypothesis that fits results
P-hacking
- data fishing: running data until receive significant result/p < 0.05
why might replication studies fail: contextually sensitive effects
ex. replicated a study in one country where gender differences aren’t as large in the original study
improvements to scientific practice
larger sample sizes
report all analyses and variables
open science collaboration
- OS framework: website to share studies/materials with other researchers
preregistration
- sharing method, hypothesis and expected results before study is conducted to eliminated chances for HARKing or P-hacking
science literature vs. meta-analysis
sci - body of scientific publication on topic
meta - comprehensive review of literature (average effect sizes for all studies)
file drawer problem
null results and opposite results rarely published
need all results in order to give accurate average
_______ do not always consider the importance of replicaility
journalists
good journalists …
summarize the body of literature on the topic
theory-testing mode
external validity often matters less than internal validity
generalization mode (consisting of frequency, association and causal claims)
fre - always in generalization mode (high external validity)
asso + cau - sometimes in generalization mode
WEIRD participants meaning
Western, Educated, Industrialized, Rich, and Democratic
a population vs. the population
a - pop of interest
the - whole population
external validity comes from ___, not __ ____
how; how many
ecological validity
an aspect of external validity in which the focus is on whether a laboratory study generalizes to real-world settings
when a study takes place in the real world, it occurs in a _____ ____ and has high _____ validity
field setting; external
experimental realism
lab research can be just as realistic as research conducted in the real world
has to be psychologically/emotionally engaging to reflect real-world feelings
external validity is important when in generalization mode, so having a ________ ______ is paramount
representative sample
ecologicial validity is also important to consider in terms of generalizing to ___-______ settings
non-laboratory
which of these is not a reason for a researcher to select a quasi-experimental design?
a. to take advantage of real-world opportunities to study phenomena and events
b. to enhance external validity
c. to avoid the ethical issues a true experiment would cause
d. to ensure internal validity
d. to ensure internal validity
The researchers found that the ability to read emotions in faces improved significantly in the kids who’d been to a camp designed to improve non-verbal communication skills, but not in the control kids, who did not go to the camp. 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 there was no significant difference between the children in the camp group and the control group
c. if the kids in the two groups were representative of children from their local school district
a. if the kids who went to camp were selected for their low levels of emotional communication skills, but the control children were not
When researchers conduct a replication study in which they have the same variables at an abstract level but use different operationalizations of each variables, what type of study is this?
a. direct replication
b. conceptual replication
c. replication on-plus-extension
d. meta-analysis
b. conceptual replication
In a longitudinal study to investigate the relationship between social media use and grades over time. Which pattern of cross-lag correlations would indicate that social media use leads to lower grades?
a. grades at year 1 shows a weak correlation with social media use at year 2, but social media use at year 1 shows a strong correlation with grades at year 2
b. grades at year 1 shows a weak correlation with social media use at year 2, but social media use at year 1 shows a weak correlation with grades at year 2
c. grades at year 1 shows a strong correlation with social media use at year 2, but social media use at year 1 shows a weak correlation with grades at year 2
d. grades at year 1 shows a strong correlation with social media use at year 2, and social media use at year 1 shows a strong correlation with grades at year 2
a. grades at year 1 shows a weak correlation with social media use at year 2, but social media use at year 1 shows a strong correlation with grades at year 2
Which of the following sentences describes a moderator for the relationship between risk taking and liking spicy foods?
a. the relationship between liking spicy foods and risk taking is the same for people in cities and in rural areas
b. older adults tend to like spicy foods less than younger adults
c. there is a positive relationship between liking spicy foods and risk taking for men, but not relationship for women
c. there is a positive relationship between liking spicy foods and risk taking for men, but not relationship for women
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 = -.35
c. r = -1.0
d. r = .45
d. r = .45
A researcher conducted an experiment with individuals with different levels of self-esteem to investigate the effect of positive self-statements on mood (wood, perunovic, & lee, 2009). They found that the moods of high self-esteem people are more positive than the moods of low self-esteem people. What is this an example of?
a. main effect
b. spreading interaction
c. interaction effect
d. crossover interaction
a. main effect
a psychiatrist wants to see if a new anxiety medication in addition to his normal medication would work better for her client. she introduces the medication and administers it for 3 months before slowly getting her client off of the new anxiety medication. when her clients is off the new anxiety medication he reports feeling more anxious than when he was on it. what type of design did the psychiatrist use?
a. interrupted time series design
b. stable-baseline design
c. reversal design
d. multiple-baseline design
c. reversal design
which of the following statements is an example of a mediator of the relationship between facebook use and college grades?
a. Facebook use and college grades only correlated with each other because they are both related to the difficulty of the major. Students in more difficult majors get worse grades, and those in difficult majors have less time to use Facebook.
b. Facebook use and college grades are correlated because Facebook use leads to less time studying, which leads to lower grades.
c. Facebook use and college grades are more strongly correlated among non-athletes, and less strongly correlated among athletes
b. Facebook use and college grades are correlated
because Facebook use leads to less time studying, which leads to lower grades.
Suppose a research team compared how high or low self esteem participants responded to three kinds of self-statements: positive, negative, and no statements. What kind of design would this be?
a. 6 x 1
b. 2 × 2
c. 2 x 2 x 2
d. 2 × 3
d. 2 x 3
When is an outlier most likely to be problematic?
a. When there is a small sample size and the outlier is extreme on one of the variables
b. When there is a small sample size and the outlier is extreme on both of the variables
c. When there is a large sample size and the outlier is extreme on both of the variables
d. When there is a large sample size and the outlier is extreme on one of the variables
b. When there is a small sample size and the outlier is extreme on both of the variables
A researcher in England conducted a study to investigate the relationship between personality disorders and parenting styles. Their first analysis of the data they collected came out with a significance value of 0.09 so they ran their analyses again and again until their significance value was 0.04. What unethical practice did this researcher follow?
a. p-hacking
b. The research er didn’t follow an unethical practice
c. Significance fishing
d. HARKing
a. p-hacking
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
A headline in Yahoo! News made the following (bivariate) association claim:
“Facebook users get worse grades in college” (Hsu, 2009). The two variables in this headline are
a. Level of Facebook use and college grades
b High grades and low grades
c. High Facebook use and low Facebook use
a. Level of Facebook use and college grades
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
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. How strong is the effect?
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
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 likely to get better grades?
d
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
A headline about social media use makes the following (bivariate) association claim: “Social media use is linked to lower grades in college.” The two variables in this headline are:
a. Social media use and quality of grades.
b. High social media use or low social media use.
c. Good grades or poor grades.
a
Suppose a researcher uses a longitudinal design to study the relationship between social media use (e.g., Instagram and Snapchat) and grades over time. She measures both of these variables in Year 1 and then measures both variables again in Year 2. Which pattern of cross-lag correlations would indicate that social media use leads to lower grades (rather than the reverse)?
a. Grades at Year 1 shows a strong correlation with social media use at Year 2, but social media use at Year 1 shows a weak correlation with grades at Year 2.
b. Grades at Year 1 shows a weak correlation with social media use at Year 2, but social media use at Year 1 shows a strong correlation with grades at Year 2.
c. Grades at Year 1 shows a strong correlation with social media use at Year 2, and social media use at Year 1 shows a strong correlation with grades at Year 2.
b
Consider this statement: “People who use social media got worse grades in college, even when the researchers controlled for the level of college preparation (operationalized by SAT scores) of the students.” What does it mean?
a. Social media use and grades are correlated only because both of these are associated with SAT score.
b. SAT score is a third variable that seems to explain the association between social media use and grades.
c. SAT score can be ruled out as a third variable explanation for the correlation between social media use and college grades.
c
Which of the following statements is an example of a mediator of the relationship between social media use and college grades?
a. Social media use and college grades are more strongly correlated among nonathletes, and less strongly correlated among athletes.
b. Social media use and college grades are only correlated with each other because they are both related to the difficulty of the major. Students in more difficult majors get worse grades, and those in difficult majors have less time to use social media.
c. Social media use and college grades are correlated because social media use leads to less time studying, which leads to lower grades.
c
A news outlet reported on a study of people with dementia. The study found that among patients with dementia, bilingual people had been diagnosed 3–4 years later than those who were monolingual. What are the variables in this bivariate association?
a. Being bilingual or monolingual
b. Being bilingual or not, and age at dementia diagnosis
c. Age at dementia diagnosis
b
The journalist reported that the relationship between bilingualism and age at diagnosis did not change, even when the researchers controlled for level of education. What does this suggest?
a. That the relationship between bilingualism and dementia onset is probably attributable to the third variable: level of education.
b. That the relationship between bilingualism and dementia onset is not attributable to the potential third variable: level of education.
c. That being bilingual can prevent dementia.
b
Researchers speculated that the reason bilingualism is associated with later onset of dementia is that bilingual people develop richer connections in the brain through their experiences in managing two languages, and these connections help stave off dementia symptoms. This statement describes:
a. A mediator
b. A moderator
c. A third variable
a
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
d. Reversal design
a
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 with a group of sixth graders from the same school who had not attended the camp. The kids were tested on how well they could read emotions in faces. The camp group took the emotion test on Monday and Friday (the first and last days 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 time-series design
c. Nonequivalent control group posttest-only design
d. Nonequivalent control group pretest/posttest design
d
For 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
The researchers found that the ability to read emotions in faces improved significantly in the kids who had 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 not representative of children from their local school district.
c. If the sample size of the study was very small.
a
A psychologist is working with four siblings, all of whom exhibit violent behavior toward one another. The children’s parents are instructed to record the number of violent behaviors each child exhibits in the hour before dinner 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
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
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
When researchers conduct a replication study in which they have the same variables at an abstract level but use 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
Which of these new research practices is most relevant for preventing HARKing?
a. Open data
b. Open materials
c. Preregistration
d. Using a larger sample
c
Which of the following claims is most likely to have been tested in generalization mode?
a. Four out of 10 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
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
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
