A
;)
Arithmetic
Mean - The average of a group of numbers.
B
Bimodal
- Two modes in a set of data.
C
Census
- When a researcher gathers data from thee whole population for a given
measurement of interest.
Classes
- Used to describe the sets or categories of data in which they
are divided.
Class
Endpoint - The highest value in a class interval.
Class
Midpoint - For any given class interval of a frequency distribution,
the value halfway across the class interval. The average of the class
endpoints.
Class
Width - The approximate width determined for the classes in a Frequency
Distribution.
Continuous Data -
Contains values between
major divisions, like 30.1, 30.2, 30.3, etc. and not just 30, 31, 32,
etc. The ages of students in a class would be Continuous Data. (see Discrete
Data also)
Cumulative
Frequency - A running total
of frequencies through the classes of a frequency distribution. (see Relative
Frequency and Frequency
Distribution
also)
D
Discrete
Data - Contains no values between
the major divisions, like 30, 31, 32, etc. and not 30.1, 30.2, 30.3,
etc. Test scores for a class would be Discrete Data. (see Continuous
Data also)
Descriptive
Statistics - When a
researcher is using data gathered on a group to describe or reach
conclusions about that same group only. (see Inferential
Statistics
also)
E
Empirical
Rule - A guideline that states the approximate percentage of
values that fall within a given number of standard deviations of a mean
of a set of data that are normally distributed.
F
Frequency
Distribution - Grouped
data. A summary of data that are presented in the form of class
intervals and frequencies. ( see Cumulative
Frequency and Relative
Frequency also)
Frequency
Polygon - A graph construed by
plotting a dot for the frequencies at the class midpoints and
connecting the dots. (see Histogram,
Ogive, Pie
Chart, or Stem
and Leaf Plot also)
G
Grouped
Data - Data that have been organized
into a frequency distribution. (see Ungrouped
Data also)
H
Histogram
- A type of vertical bar chart
constructed by graphing
line segments for the frequencies of classes
acros
s the class intervals and connecting each to the X axis to form a
series of rectangles. (see Fre
quenc
y
Polygon, Ogive,
Pie Chart, or Stem
and Leaf Plot also)
I
Inferential
Statistics - When a
researcher gathers data from a sample and uses the statistics generated
to reach conclusions about the population from which the sample was
taken. (see Descriptive
Statistics also)
Interval
Level Data - The next - to -
highest level of data. These data have all properties of ordinal level
data; in addition, intervals between numbers have meaning. (see Nominal
Level Data, Ordinal Level Data,
or Ratio
Level Data also)
J
Joint
Probability - The probability of the intersection occurring, or the
probability of two or more things happening at once.
K
Kurtosis
- The amount of peakedness of a distributtion.
L
Leptokurtic
- Distributions that are high and thin.
M
Metric
Data - Interval and ration level data;
quantitative data. (see Nonmetric
Data also)
N
Nominal
Level Data - The lowest level of
data measurement; used only to classify or categorize. (see Ordinal
Level Data, Interval Level Data,
or Ratio
Level Data also)
Nonmetric
Data -
Nominal and ordinal level
data; qualitative data. (see Metric
Data also)
Nonparametric
Statistics - A class
of statical techniques that make few assumptions about the population
and are particularly applicable to nominal and ordinal level data. (see
Parametric Statistics
also)
O
Ogive - A
cumulative or frequency
polygon. The Ogive is plotted by graphing a dot at each class end point
for the cumulative frequency value and connecting the
dots. (see Frequency Polygon, Histogram,
Pie
Chart, or Stem and Leaf Plot
also)
Ordinal
Level
Data - The next higher
level of data from nominal level data; can be used to order or rank
items, objects, or people. (see Nominal
Level Data, Interval
Level Data, or Ratio
Level Data also)
P
Parameter
- A descriptive measure of the population.
Parametric
Statistics - A class of
statical techniques that contain assumptions about the population and
that are generally used only with interval and ration level data. (see Nonparametric
Statistics
also)
Pie
Charts - A circular
depiction of data where
the area of the whole pie represents 100% of the data being studied and
slices represent a percentage breakdown of the sublevels. (see Frequency
Polygon, Histogram,
Ogive,
or Stem and Leaf Plot
also)
Population
- A collection of persons, objects, or items of interest.
Q
Quartiles
- Measures of location that divide a grouup of data into four
subgroups or parts.
Qualitative
Data - Seen in the form of names or labels, used to
categorize or describe like items.
Quantitative
Data - Seen in the form of a measurement, how much or how
many of certain items.
R
Range
- The difference between the greatest andd least numbers in a set of
numbers.
Ratio
Level Data
- The highest level of
data measurement. Contains the same properties as interval level data
but, in addition, zero has meaning and represents the absence of the
phenomenon being measured. (see Nominal
Level Data, Ordinal
Level Data, or Interval
Level Data also)
Relative
Frequency - The proportion of
the total frequencies that fall into any given class interval in a
frequency distribution. (see Cumulative
Frequency and Frequency
Distribution also)
S
Sample
- A portion of the whole.
Statistic
- A descriptive measure of a sample.
Statistics
- A science dealing with the collection, analysis,
interpretations, and presentation of numerical data.
Stem
and Leaf
Plot - A plot of numbers
constructed by dividing each number into two parts, a stem and a leaf.
The leftmost digits are the steams and the rightmost digits are the
leaves. (see Frequency Polygon, Histogram,
Ogive, or Pie
Chart also)
T
Telescoping
Error - When a respondent attributes an event to a wrong
time period.
U
Ungrouped
Data - Raw data, or data that have
not been organized into a frequency distributions. (see Grouped
Data also)
V
Variance
- The average of the squared deviations aabout the arithmetic
mean for a set of numbers.
Variable- A characteristic that differs from case to case and defines what is measured or classified.
W
Wording Effects- Confusing or leading questions that introduce a bias and effect a survey's outcome.
Z
Z
Score - the number of standard deviations a value is above or below the
mean of a set of numbers.
