Download BASIC STATISTICAL CONCEPTS

BASIC STATISTICAL
CONCEPTS
Chapter Three
CHAPTER OBJECTIVES
Understand (and in some cases be able to
calculate) the following:
Scales of
Measurement
Measures of central
tendency (mean,
median, mode)
Frequency distribution
Range
Variance
Standard Deviation
Normal curve
Skewed distribution
Correlations
SCALES OF MEASUREMENT
In descriptive statistics, there are four
scales of measurement that can be
used to explain data:
1. NOMINAL
2. ORDINAL
3. INTERVAL
4. RATIO
NOMINAL
Data created by assigning
observations into various
independent categories and then
counting the frequency of
occurrence within each of the
categories.
ORDINAL
A scale in which scores
indicate only relative
amounts or rank order
INTERVAL
A scale in which equal differences
in scores represent equal
differences in amount of the
property measured, but with an
arbitrary zero point.
RATIO
All the properties of an
interval scale with the
additional property of zero
indicating a total absence
being measured.
MEASURES OF CENTRAL
TENDENCY
MEAN
MEDIAN
MODE
FREQUENCY DISTRIBUTION
Expresses how
often a score
occurs in a set of
data.
RANGE
The difference between the high score and
the low score in the distribution
VARIANCE
A statistical concept that tells you the
spread of scores within a distribution
STANDARD DEVIATION
The spread of scores around
the mean.
Calculated by taking the
square root of the variance.
NORMAL DISTRIBUTION
Hypothetically represents the way test
scores would fall if a particular test is
given to every single student the same
age or grade in the population for whom
the test was designed.
NORMAL CURVE
Also referred to as the bell curve
Never changes
SKEWED DISTRIBUTIONS
A distribution in which the majority
of scores fall at either the high end,
or the low end rather than
the middle of the distribution.
CORRELATIONS
Tell us the relationship between two
variables. There are three types:
Positive Correlation
Negative Correlation
Zero Correlation
CHAPTER OBJECTIVES
Understand (and in some cases be able to
calculate) the following:
Scales of
Measurement
Measures of central
tendency (mean,
median, mode)
Frequency distribution
Range
Variance
Standard Deviation
Normal curve
Skewed distribution
Correlations
THE END