For each of the following research questions, you will read an independent and dependent samples study
to test that research question. Identify which study used independent and which used dependent samples.
(Use these instructions for questions 1-5).
How does winning influence self-efficacy (or beliefs in one’s ability) among high school sports athletes?
Study 1: Researchers hypothesized that the more wins a team has, the more teammates will believe in
their own abilities (self-efficacy). To test this, they selected a group of sports athletes from teams with few
wins during the previous season and a second group of sports athletes from teams with many wins during
the previous season. They tested whether self-efficacy significantly differed between groups.
Study 2: Researchers hypothesized that the more wins a team has, the more teammates will believe in
their own abilities (self-efficacy). To test this, they measured self-efficacy among athletes during a winning
season, and again during a losing season the following year. They tested whether the difference in selfefficacy between winning and losing seasons was significantly different.
Question 2.
Will levels of the brain chemical dopamine increase in response to food rewards?
Study 1: Researchers hypothesized that dopamine would increase in response to a high-fat food (reward)
versus a similar low-fat food. To test this, they presented four adult female Macaca fascicularis monkeys
with a high- and low-fat raisin and measured the levels of dopamine in the brain in response to each
reward. They tested whether the difference in dopamine levels was significantly different.
Study 2: Researchers hypothesized that the levels of dopamine would increase in response to a larger food
reward. To test this, they had animal subjects press a lever to receive a food reward and measured levels
of dopamine in the brain in response to this reward. One group received a small food reward and a second
group received a large food reward. They tested whether dopamine levels significantly differed between
groups
Question 3:
Do English as a second language (ESL) children have the same knowledge of word meanings as English
as a first language (ELI) children?
Study 1: Researchers hypothesized that ESL children would have greater difficulty in phonological
awareness (the ability to notice, think about, or manipulate the individual sounds in words). To test this,
they had one group of ESL children and a second group of ELI children complete a phonological
awareness assessment and recorded the scores. They tested whether phonological awareness
assessment scores significantly differed between groups.
Study 2: Researchers hypothesized that ESL children would have the same knowledge of word meanings
as do their ELI relatives. To test this, they recorded scores on a vocabulary knowledge assessment for ESL
children and comparison ELI relatives (of similar ages). They tested whether the difference in vocabulary
knowledge assessment scores between these related children was significantly different.
Question 4
How do psychosocial attitudes (those based on the interaction between the individual and the social
environment) toward romantic love vary by race/culture?
Study 1: Researchers hypothesized that cultures focused on group identity (collectivist) would place less
emphasis on romantic love compared with cultures focused on individual identity (individualistic). To test
this, they collected a sample of Chinese (collectivist) and American (individualistic) adolescents and had
them complete a romantic love assessment survey. They tested whether scores on this survey significantly
differed between groups.
Study 2: Researchers hypothesized that psychosocial attitudes toward love in individualistic cultures would
be more negative following the loss of a romantic relationship. To test this, they recorded perceptions of
love among a group of American college students during and following a romantic relationship. They tested
whether the difference in perceptions of love during and after a romantic relationship was significantly
different.
Question
Does snacking between meals reduce the number of calories consumed in a meal?
Study 1: Researchers hypothesized that snacking between meals would only reduce calories consumed inthe meal if participants thought of the foods as “snack foods” (referred to as cognitive satiety). To test this,
on 1 day they gave a group of participants 100 kilocalories (kcal) of a food they thought of as a snack food
and recorded the number of calories consumed in the subsequent meal. On the second day, they gave the
same group of participants 100 kcal of a food they thought of as a “meal food” and recorded the number of
calories consumed in the subsequent meal. They tested whether the difference in calories consumed in the
meal from Day 1 to Day 2 significantly differed.
Study 2: Researchers hypothesized that snacking between meals would reduce the number of calories
consumed in a meal. To test this, they recorded the number of calories consumed in a meal following one
snack (Group 1S) and following three snacks (Group 3S). The meal was buffet style, meaning that
participants could consume as much as they wanted in the meal. The researchers tested whether calories
consumed in the meal significantly differed between groups.
Question 6
How are related samples different from independent samples?
Question 7
Which type of repeated-measures design can only be used with two groups?
Question 8
Define difference scores. How does using difference scores increase the power of a related samples t test?
Question 9
State three advantages for using related samples in behavioral research.
Question 10.
What are the assumptions for a related-samples t test?
Question 11
Describe in words the formula for an estimated Cohen’s d for two related samples.
Question 12
Question 12 5 pts
State whether each of the following related samples t test is significant for a two-tailed test at a .05 level of
significance.
(a) t(30)=3.220
(b) t(12)=2.346
(c) t(18)=2.034
(d) t(60)=1.985