Psych 289 Chapter 2 (Research Enterprise in Psychology)
Questions With Complete Solutions
What does a small standard deviation indicate about variability?
(pp. 60-62)
small standard deviation indicates smaller variability
normal distribution curve
a symmetrical, bell-shaped curve that describes the distribution
of many types of data; most scores fall near the mean (about 68
percent fall within one standard deviation of it) and fewer and
fewer near the extremes.
What are relative measures? (61)
Psychological tests- relative measures that assess how people
score on a trait in comparison to other people
What is a percentile score? (61)
Indicates the percentage of people who score at or below a
particular score
e.g. if you score at the 60th percentile, it means that 60% of
people taking the same test either score the same or below you
and the 40% scored above you
If your percentile score on the final exam in this course is 10%,
have you done relatively well or poorly on the exam? Explain.
(p. 61)
,you would have poorly on the exam because only 10% of the
group scored the same or below you and the remaining 90%
scored above you.
What is a correlation coefficient and correlation?
1. correlation- when two variables are related: class attendance
and class grades
2. Correlation coefficient- a statistical measure of the
relationship between two variables and indicates
a.direction either positive or negative
b. how strongly the variables are related
What is a positive correlation and negative correlation?
1. Positive correlation- indicates that two variables co-vary in
the same direction
e.g. high scores on a X variable are associated with high scores
, on the Y variable: high scores in high school GPA are positively
correlated with high GPA in universities
2. Negative correlation- indicates that two variables co-vary in
the opposite direction
e.g. high score on the X variable but low score on the Y
variable: high number of absences in school will show lower
grades
What is the strength of the correlation, and how is this indicated
in the correlation coefficient? (pp. 62-63)
Size of the coefficient indicates the strength of an association
between two variables
1. varies between 0 and +1.00 if positive
2. between 0 and -1.00 if negative
3. coefficient near zero indicates no relationship between the
variables
Questions With Complete Solutions
What does a small standard deviation indicate about variability?
(pp. 60-62)
small standard deviation indicates smaller variability
normal distribution curve
a symmetrical, bell-shaped curve that describes the distribution
of many types of data; most scores fall near the mean (about 68
percent fall within one standard deviation of it) and fewer and
fewer near the extremes.
What are relative measures? (61)
Psychological tests- relative measures that assess how people
score on a trait in comparison to other people
What is a percentile score? (61)
Indicates the percentage of people who score at or below a
particular score
e.g. if you score at the 60th percentile, it means that 60% of
people taking the same test either score the same or below you
and the 40% scored above you
If your percentile score on the final exam in this course is 10%,
have you done relatively well or poorly on the exam? Explain.
(p. 61)
,you would have poorly on the exam because only 10% of the
group scored the same or below you and the remaining 90%
scored above you.
What is a correlation coefficient and correlation?
1. correlation- when two variables are related: class attendance
and class grades
2. Correlation coefficient- a statistical measure of the
relationship between two variables and indicates
a.direction either positive or negative
b. how strongly the variables are related
What is a positive correlation and negative correlation?
1. Positive correlation- indicates that two variables co-vary in
the same direction
e.g. high scores on a X variable are associated with high scores
, on the Y variable: high scores in high school GPA are positively
correlated with high GPA in universities
2. Negative correlation- indicates that two variables co-vary in
the opposite direction
e.g. high score on the X variable but low score on the Y
variable: high number of absences in school will show lower
grades
What is the strength of the correlation, and how is this indicated
in the correlation coefficient? (pp. 62-63)
Size of the coefficient indicates the strength of an association
between two variables
1. varies between 0 and +1.00 if positive
2. between 0 and -1.00 if negative
3. coefficient near zero indicates no relationship between the
variables
