PSY 201 STONY BROOK UNIVERSITY STATISTICS STUDY GUIDE &
PRACTICE QUESTIONS 2026/2027
What are statistics, broadly speaking? - Correct answer ✔✔ mathematical procedures for
organizing, summarizing and interpreting info.
used in:
- healthcare
-foreign policy
- sports
- politics
What is a population and sample? - Correct answer ✔✔ population: all individuals (or items) in
the group of interest.
when the population is too large to study we use a...
sample: a set of individuals (or items) selected to represent the population.
What is a constant? Variable? - Correct answer ✔✔ variable: any characteristics, # or quantity
that can be measured or counted. AKA data item
constant: doesn't change
What is a parameter, and a statistic? How are they similar and different? - Correct answer ✔✔
population parameter: the value of interest from the population
sample statistic: the value collected from the sample
similar: values collected from a group
different: one comes from a sample and the other comes from a population
,What is the difference between descriptive and inferential statistics? - Correct answer ✔✔
Descriptive statistics summarize the characteristics of a data set. Inferential statistics allow you
to test a hypothesis or assess whether your data is generalizable to the broader population.
What does the experimental method offer relative to the correlational method? Describe the
two. - Correct answer ✔✔ experimental method: manipulate a variable, control all confounding
variables, tests cause-effect relationships
correlational method: no manipulation, testing relationships between 2 measured variables
What is the difference between the experimental and quasi experimental methods? - Correct
answer ✔✔ experimental method: manipulate a variable, control all confounding variables,
tests cause-effect relationships
quasi experimental method: manipulate a variable, unable to control all confounding variables,
unable to test cause-effect relationships.
difference: experimental tests cause-effect relationships, and controls confounding variables,
quasi doesn't.
What do the quasi-experimental and correlational methods have in common? - Correct answer
✔✔ Quasi-experiments usually select only a certain range of values of an independent variable,
while a typical correlational study measures all available values of an independent variable.
What is a confounding variable? - Correct answer ✔✔ a variable that influences both the
dependent variable and independent variable
What is the scientific method? - Correct answer ✔✔ an empirical method of acquiring
knowledge.
observation/question->research->hypothesis->test->analyze data->conclusions
What is a hypothesis? -What is a hypothetical construct? What is an operational definition? -
Correct answer ✔✔ hypothesis: testable on the basis of observed data modeled as the realized
values taken by a collection of random variables.
, hypothetical construct: explanatory variable which is not directly observable (depression, love,
personality traits)
operational definition: defines a construct in terms of specific operations or procedures and the
measurements that result form them
What are the four scales of measurement? Give examples of each. - Correct answer ✔✔
Nominal: naming/classifying (major)
Ordinal: ordering (seniority at a job)
Interval: no true zero (temperature)
Ratio: has an absolute zero (# of plane crashes, height/weight, distance moved while wearing a
fitbit)
What is a continuous scale of measurement in contrast to a discrete scale of measurement? -
Correct answer ✔✔ continuous: infinite # of possible values, divisible into fractional parts (5.25
length, 5.2345 lbs)
discrete: variables that consist of separate indivisible categories, whole numbers only (children
in a family, number of tv's in a household)
What is the difference between descriptive and inferential statistics? - Correct answer ✔✔
descriptive: when we use statistics to organize, summarize, and simplify information
inferential: when sample statistics are used to estimate the population parameter
When do you use bar graphs instead of frequency distribution histograms? - Correct answer
✔✔ use a frequency histogram when...
- the #'s or categories are on an interval or ratio scale
use a bar graph when...
- x-axis variable is from a nominal/ordinal scale (doesn't touch)
PRACTICE QUESTIONS 2026/2027
What are statistics, broadly speaking? - Correct answer ✔✔ mathematical procedures for
organizing, summarizing and interpreting info.
used in:
- healthcare
-foreign policy
- sports
- politics
What is a population and sample? - Correct answer ✔✔ population: all individuals (or items) in
the group of interest.
when the population is too large to study we use a...
sample: a set of individuals (or items) selected to represent the population.
What is a constant? Variable? - Correct answer ✔✔ variable: any characteristics, # or quantity
that can be measured or counted. AKA data item
constant: doesn't change
What is a parameter, and a statistic? How are they similar and different? - Correct answer ✔✔
population parameter: the value of interest from the population
sample statistic: the value collected from the sample
similar: values collected from a group
different: one comes from a sample and the other comes from a population
,What is the difference between descriptive and inferential statistics? - Correct answer ✔✔
Descriptive statistics summarize the characteristics of a data set. Inferential statistics allow you
to test a hypothesis or assess whether your data is generalizable to the broader population.
What does the experimental method offer relative to the correlational method? Describe the
two. - Correct answer ✔✔ experimental method: manipulate a variable, control all confounding
variables, tests cause-effect relationships
correlational method: no manipulation, testing relationships between 2 measured variables
What is the difference between the experimental and quasi experimental methods? - Correct
answer ✔✔ experimental method: manipulate a variable, control all confounding variables,
tests cause-effect relationships
quasi experimental method: manipulate a variable, unable to control all confounding variables,
unable to test cause-effect relationships.
difference: experimental tests cause-effect relationships, and controls confounding variables,
quasi doesn't.
What do the quasi-experimental and correlational methods have in common? - Correct answer
✔✔ Quasi-experiments usually select only a certain range of values of an independent variable,
while a typical correlational study measures all available values of an independent variable.
What is a confounding variable? - Correct answer ✔✔ a variable that influences both the
dependent variable and independent variable
What is the scientific method? - Correct answer ✔✔ an empirical method of acquiring
knowledge.
observation/question->research->hypothesis->test->analyze data->conclusions
What is a hypothesis? -What is a hypothetical construct? What is an operational definition? -
Correct answer ✔✔ hypothesis: testable on the basis of observed data modeled as the realized
values taken by a collection of random variables.
, hypothetical construct: explanatory variable which is not directly observable (depression, love,
personality traits)
operational definition: defines a construct in terms of specific operations or procedures and the
measurements that result form them
What are the four scales of measurement? Give examples of each. - Correct answer ✔✔
Nominal: naming/classifying (major)
Ordinal: ordering (seniority at a job)
Interval: no true zero (temperature)
Ratio: has an absolute zero (# of plane crashes, height/weight, distance moved while wearing a
fitbit)
What is a continuous scale of measurement in contrast to a discrete scale of measurement? -
Correct answer ✔✔ continuous: infinite # of possible values, divisible into fractional parts (5.25
length, 5.2345 lbs)
discrete: variables that consist of separate indivisible categories, whole numbers only (children
in a family, number of tv's in a household)
What is the difference between descriptive and inferential statistics? - Correct answer ✔✔
descriptive: when we use statistics to organize, summarize, and simplify information
inferential: when sample statistics are used to estimate the population parameter
When do you use bar graphs instead of frequency distribution histograms? - Correct answer
✔✔ use a frequency histogram when...
- the #'s or categories are on an interval or ratio scale
use a bar graph when...
- x-axis variable is from a nominal/ordinal scale (doesn't touch)
