PSYCH 203 Final || with 100% Accurate Solutions.
What is the purpose of correlational research correct answers Purpose is to describe the
relationship between two or more naturally occurring(not experimentally manipulated) variables
What variable is the predictor correct answers X
What variable is the outcome correct answers Y
What is measure correct answers -variables representing two or more constructs of interest
How can measurement be taken correct answers Observation, physiological, self report, etc.
-all considerations for high quality measurement apply
Scale of measurement correct answers Interval or ratio
-for a pearson correlation analysis, both variables must be measured on a continuous scales
Relationships are described by correct answers -corrlation coefficient
-ranges from -1 to +1
-scatterplots (visual)
-data points and trend lines
How do we know if variables are indeed related (correlated) correct answers We collect
measurements of the two variables andthen compute r
What does r indicate correct answers The extent of a linear relationship between two variables
1. Strength
2. Direction
3. Rangs from -1 t +1
What is a correlation coefficient correct answers It represents the fraction o the variation in one
variable that may be explained by the other variable
When do we typically use a correlation coefficient correct answers To express degree of co-
variation
Direction of relationship: positive correct answers Scoers on both variables up or both down
Negative direction correct answers Scores on one go up while other goes down
High magnitude of relationship correct answers Strong relationship (close to -1. Or +1)
Low magnitude of relationship correct answers Weak relationship (closer to 0)
Two important parts of scatterplots correct answers Data points and trend lines
, Trend line equals what correct answers Slope or direction of effect
What is leverage correct answers When an outlier is influential and can pull trend line up or
down
Types of correlations correct answers -positive
-negative
-none
-curvlinear
Limitations of correlation coefficients correct answers -curvilinear relationship
-restricted range
-outliers
-measure reliability
Curvilinear relationship correct answers Correlations only work with linear relationships
-might have two separate associations going in different directions
Restricted range correct answers When not enough data in your sample it can limit the
magnitude of the correlation and conclude there is not a relationship
Outliers correct answers Defined as + or - 3 SD from the mean
-these can heavily skew your correlation coefficient, likely making it smaller in magnitude
What is measure reliability correct answers Less reliable measures, lower correlation coefficients
-if the measure isn't reliable it won't accurately capture the variable you are investigating making
relationships weaker
Types of correlation correct answers -pearson
-spearman rank order
-point biserial
-phi coefficient
Pearson correlation correct answers Both variables are interval or ratio (ex: GPA and days
attnded class )
-this is most commonly used
Spearman rank-order correlation correct answers One or both variables are ordinal (or rank) ex:
high school rank and college rank of collge attended
Point biserial correlation correct answers -one dichtomous variable and the other is ratio or
interval (ex:gender and depression)
-dichotomous variables are like nominal, but they only have two levels, such as gender
Phi coefficient correct answers Both variabls are dichotomous (ex: gender and high school
dropout)
What is the purpose of correlational research correct answers Purpose is to describe the
relationship between two or more naturally occurring(not experimentally manipulated) variables
What variable is the predictor correct answers X
What variable is the outcome correct answers Y
What is measure correct answers -variables representing two or more constructs of interest
How can measurement be taken correct answers Observation, physiological, self report, etc.
-all considerations for high quality measurement apply
Scale of measurement correct answers Interval or ratio
-for a pearson correlation analysis, both variables must be measured on a continuous scales
Relationships are described by correct answers -corrlation coefficient
-ranges from -1 to +1
-scatterplots (visual)
-data points and trend lines
How do we know if variables are indeed related (correlated) correct answers We collect
measurements of the two variables andthen compute r
What does r indicate correct answers The extent of a linear relationship between two variables
1. Strength
2. Direction
3. Rangs from -1 t +1
What is a correlation coefficient correct answers It represents the fraction o the variation in one
variable that may be explained by the other variable
When do we typically use a correlation coefficient correct answers To express degree of co-
variation
Direction of relationship: positive correct answers Scoers on both variables up or both down
Negative direction correct answers Scores on one go up while other goes down
High magnitude of relationship correct answers Strong relationship (close to -1. Or +1)
Low magnitude of relationship correct answers Weak relationship (closer to 0)
Two important parts of scatterplots correct answers Data points and trend lines
, Trend line equals what correct answers Slope or direction of effect
What is leverage correct answers When an outlier is influential and can pull trend line up or
down
Types of correlations correct answers -positive
-negative
-none
-curvlinear
Limitations of correlation coefficients correct answers -curvilinear relationship
-restricted range
-outliers
-measure reliability
Curvilinear relationship correct answers Correlations only work with linear relationships
-might have two separate associations going in different directions
Restricted range correct answers When not enough data in your sample it can limit the
magnitude of the correlation and conclude there is not a relationship
Outliers correct answers Defined as + or - 3 SD from the mean
-these can heavily skew your correlation coefficient, likely making it smaller in magnitude
What is measure reliability correct answers Less reliable measures, lower correlation coefficients
-if the measure isn't reliable it won't accurately capture the variable you are investigating making
relationships weaker
Types of correlation correct answers -pearson
-spearman rank order
-point biserial
-phi coefficient
Pearson correlation correct answers Both variables are interval or ratio (ex: GPA and days
attnded class )
-this is most commonly used
Spearman rank-order correlation correct answers One or both variables are ordinal (or rank) ex:
high school rank and college rank of collge attended
Point biserial correlation correct answers -one dichtomous variable and the other is ratio or
interval (ex:gender and depression)
-dichotomous variables are like nominal, but they only have two levels, such as gender
Phi coefficient correct answers Both variabls are dichotomous (ex: gender and high school
dropout)
