PSYC 301 EXAM 1 STUDY GUIDE
Statistics - Answers - a set of tools and techniques used for describing, organizing,
and interpreting information or data
Goals of science and how statistics help achieve those - Answers - Description- How
do people behave?
Prediction- Identifying the factors that influence behavior
Explanation-Identifying the underlying causes of a behavior
Research methods and statistics are the ways we learn and discover
Descriptive Statistics - Answers - used to organize and describe data
- Ex: counts, means, percentenges
Inferential Statistics - Answers - used to make inferences about a larger group from a
smaller group
- The next step after description
Sample - Answers - the group you actually collect data from
Population - Answers - the group you are actually interested in drawing some
conclusions about
Variable - Answers - something that can change or have different values for different
individuals
Data - Answers - information collected from the sample on the variable we are
interested in
Continuous Data - Answers - data measured on a continuum, all numbers between
two end points are possible scores
- Ex: height, weight, age
Categorical Data - Answers - data that sorts people into categories, only so many
options for the variable
- Ex: gender, major, experimental condition
Central Tendency - Answers - a single number number that represents a group of
scores
-Mean
-Median
-Mode
Mean - Answers - the average value of a group of numbers
- most common
, X-bar = (Σx)/n
Median - Answers - the midpoint in a set of scores
-point at which half of the scores are bigger and
half of the scores are smaller
List values in order and find middlemost score
Percentile Points - Answers - refers to the percentage of cases equal to and below a
certain point in a group of scores
-The median is the 50% percentile
Mode - Answers - the value that occurs most frequently in data
- typically used with categorical data
Bimodal - Answers - a data set with two modes
When to use which measure of central tendency - Answers - Use MODE when the
data are categorical
Use MEAN when the data are continuous and you don't have any extreme scores
Use MEDIAN when the data are continuous and you think mean is misleading
-When in doubt report both
Variability - Answers - The extent to which the scores in a data set tend to vary from
each other and from the mean.
-Range
-Standard Deviation
-Variance
Why is it important? - Answers - A set can have the same sample size and the same
mean by have a different amount of variability
Range - Answers - the difference between the highest and lowest scores in a
distribution
- most general measure of variability
- ignores the middlemost values
- emphasis on extreme scores
r=h-l
Standard Deviation - Answers - the average amount of variability in a set of scores
- most common measure of variability
- low SD data points are close to sample mean
- high SD data points are far away from sample
mean
s = √[(Σ(x - xbar)^2)/n-1]
Variance - Answers - standard deviation squared
Statistics - Answers - a set of tools and techniques used for describing, organizing,
and interpreting information or data
Goals of science and how statistics help achieve those - Answers - Description- How
do people behave?
Prediction- Identifying the factors that influence behavior
Explanation-Identifying the underlying causes of a behavior
Research methods and statistics are the ways we learn and discover
Descriptive Statistics - Answers - used to organize and describe data
- Ex: counts, means, percentenges
Inferential Statistics - Answers - used to make inferences about a larger group from a
smaller group
- The next step after description
Sample - Answers - the group you actually collect data from
Population - Answers - the group you are actually interested in drawing some
conclusions about
Variable - Answers - something that can change or have different values for different
individuals
Data - Answers - information collected from the sample on the variable we are
interested in
Continuous Data - Answers - data measured on a continuum, all numbers between
two end points are possible scores
- Ex: height, weight, age
Categorical Data - Answers - data that sorts people into categories, only so many
options for the variable
- Ex: gender, major, experimental condition
Central Tendency - Answers - a single number number that represents a group of
scores
-Mean
-Median
-Mode
Mean - Answers - the average value of a group of numbers
- most common
, X-bar = (Σx)/n
Median - Answers - the midpoint in a set of scores
-point at which half of the scores are bigger and
half of the scores are smaller
List values in order and find middlemost score
Percentile Points - Answers - refers to the percentage of cases equal to and below a
certain point in a group of scores
-The median is the 50% percentile
Mode - Answers - the value that occurs most frequently in data
- typically used with categorical data
Bimodal - Answers - a data set with two modes
When to use which measure of central tendency - Answers - Use MODE when the
data are categorical
Use MEAN when the data are continuous and you don't have any extreme scores
Use MEDIAN when the data are continuous and you think mean is misleading
-When in doubt report both
Variability - Answers - The extent to which the scores in a data set tend to vary from
each other and from the mean.
-Range
-Standard Deviation
-Variance
Why is it important? - Answers - A set can have the same sample size and the same
mean by have a different amount of variability
Range - Answers - the difference between the highest and lowest scores in a
distribution
- most general measure of variability
- ignores the middlemost values
- emphasis on extreme scores
r=h-l
Standard Deviation - Answers - the average amount of variability in a set of scores
- most common measure of variability
- low SD data points are close to sample mean
- high SD data points are far away from sample
mean
s = √[(Σ(x - xbar)^2)/n-1]
Variance - Answers - standard deviation squared
