PSYCHOLOGICAL
Statistics
, LESSON 1
INTRODUCTION TO STATISTICS
WHAT IS STATISTICS? BASIC CONCEPTS
- branch of math that focuses on ● VARIABLE — characteristics that can
the interpretation of a group of have different values.
numbers ● VALUES — possible numbers or
categories that a score can have.
● SCORE — particular person’s value on
THE TWO BRANCHES OF STATISTICS
a variable.
Descriptive Statistic
- organizes, summarizes, and
communicates a group of numerical
observations.
- procedures for summarizing a group
of scores or otherwise making them more
understandable.
( Example : A 20 year old has a score of 20 on
- Mainly just make a description about
the variable age. Thus, this person’s score of 20
the data obtained
is one of many possible values of age. The
- “Her weight is 50kg”
variable in this case is age)
Inferential Statistic
- Uses sample data to make general HOW TO TRANSFORM OBSERVATIONS
estimates and predictions about the INTO VARIABLES
larger population.
- drawing conclusions based on the Variable is any observation of a physical,
scores collected in a research study but attitudinal, or behavioral characteristic that
going beyond them. can take on different values.
- “80 over 100 of the students’ weight is
50kg so it’s best to assume that most ● Numeric Variable — variable whose
of the students is chubby” values are numbers (as opposed to a
nominal variable). Also called
POPULATION VS SAMPLE quantitative variables.
● Equal-Interval Variable — variable in
which the numbers stand for
Population
approximately equal amounts of
- includes all possible observations
what is being measured.
about which we’d like to know
● Rank-Order Variable — numeric
something.
variable in which the values are ranks,
such as class standing or place
Sample
finished in a race. Also called ordinal
- is a set of observations drawn from the
variables.
population of interest.
Statistics
, LESSON 1
INTRODUCTION TO STATISTICS
WHAT IS STATISTICS? BASIC CONCEPTS
- branch of math that focuses on ● VARIABLE — characteristics that can
the interpretation of a group of have different values.
numbers ● VALUES — possible numbers or
categories that a score can have.
● SCORE — particular person’s value on
THE TWO BRANCHES OF STATISTICS
a variable.
Descriptive Statistic
- organizes, summarizes, and
communicates a group of numerical
observations.
- procedures for summarizing a group
of scores or otherwise making them more
understandable.
( Example : A 20 year old has a score of 20 on
- Mainly just make a description about
the variable age. Thus, this person’s score of 20
the data obtained
is one of many possible values of age. The
- “Her weight is 50kg”
variable in this case is age)
Inferential Statistic
- Uses sample data to make general HOW TO TRANSFORM OBSERVATIONS
estimates and predictions about the INTO VARIABLES
larger population.
- drawing conclusions based on the Variable is any observation of a physical,
scores collected in a research study but attitudinal, or behavioral characteristic that
going beyond them. can take on different values.
- “80 over 100 of the students’ weight is
50kg so it’s best to assume that most ● Numeric Variable — variable whose
of the students is chubby” values are numbers (as opposed to a
nominal variable). Also called
POPULATION VS SAMPLE quantitative variables.
● Equal-Interval Variable — variable in
which the numbers stand for
Population
approximately equal amounts of
- includes all possible observations
what is being measured.
about which we’d like to know
● Rank-Order Variable — numeric
something.
variable in which the values are ranks,
such as class standing or place
Sample
finished in a race. Also called ordinal
- is a set of observations drawn from the
variables.
population of interest.
