Nature of Statistics Flashcards
is the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data.
statistics
is widely regarded as the “Father of Modern Statistics and Experimental Design”.
Sir Ronald Aylmer Fisher (1890-1962)
is a characteristic or attribute that can assume different values.
variable
are the values (measurement or observations) that the variables can assume.
data
Variables whose values are determined by chance are called
random variables
A collection of data values forms a ____. Each
value in the data set is called a _____ or _____.
data set, data value or a datum.
consists of the collection, organization, summarization, and presentation of data. In this area, the statistician tries to describe a situation.
Descriptive Statistics
consists of generalizing from samples to population, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. This area uses the concept of probability.
Inferential Statistics
consists of all subjects (human or otherwise) that are being studied
population
is a group subjects selected from a population.
sample
is a decision-making process for evaluating claims about population, based on information obtained from samples.
Hypothesis Testing
Two classifications of variables:
QUALITATIVE & QUANTITATIVE
are variables that can be placed into distinct categories, according to some characteristics or attribute.
Qualitative Variables
are numerical and can be ordered or
ranked.
Quantitative Variables
Two classifications of Quantitative variables:
DISCRETE &
CONTINUOUS
assume values that can be counted
Discrete variables
assume an infinite number of values
between any two interval between any two specific values. They are obtained by measuring and often include fractions and decimals where measures are rounded to the nearest given unit.
Continuous variables
Four classifications of how variables are categorized, counted or measured (measurement scales):
: (1) Nominal, (2) Ordinal,
(3)Interval, and (4) Ratio.
classifies data into mutually exclusive (nonoverlapping) categories in which no order or ranking can be imposed on the data.
Nominal level of measurement
classifies data into categories that can be ranked; however, precise differences between the ranks do not exist.
Ordinal level of measurement
ranks data, and precise differences between units of measure do exist; however, there is no meaningful zero.
Interval level of measurement
possesses all the characteristics of
interval measurement, and there exists a true zero. In addition, true ratios exists when the same variable is measured on two different members of the population.
Ratio level of measurement
is the most common method used to collect data.
survey
There most common survey methods are
(1) telephone survey,
(2) mailed questionnaire, and (3) personal interview.
conducts data collection over a phone
where there is no face-to-face contact happens.
telephone survey,
can be used to cover a wider geographic area than telephone survey or personal interview.
mailed questionnaire
have the advantage of obtaining in-depth
responses to questions from the person being interviewed
personal interview
Four basic methods of Sampling:
(1) Random, (2) Systematic,
(3) Stratified, and (4) Cluster Sampling.
are selected by using chance methods or
random numbers.
random samples
are obtained by numbering each subject
of the population and then selecting every kth subject.
Systematic samples
are obtained by dividing the population into
groups (called strata) according to some characteristic that is important to study, then random sampling is conducted from each
group.
Stratified Samples
are obtained by dividing the population intro
groups called clusters by some means such as geographic are or schools in a large school district. Then random selection of these clusters is conducted, and all members of the selected
cluster will be included as subjects
Cluster Samples
Some classifications of statistical studies:
(1) Observational, (2)
Experimental, and (3) quasi-experimental study.
the researcher merely observes what is
happening or what has happened in the past and tries to draw conclusions based on these observations.
Observational Study
the researcher manipulates one of the
variables and tries to determine how the manipulation influences other variables
Experimental Study
In a true experimental study, the subjects should be assigned to groups randomly. Also, the treatments should be assigned to the groups at random. Sometimes when random assignment is not possible, researchers use intact groups. When these groups are used, the study is said to be a
quasiexperimental study.
is the one that is being manipulated
also called explanatory variable
Independent Variable
is the resultant variable also called
outcome variable
Dependent Variable
In experimental study, there are groups called
Treatment Group and Control Group
____ receives a specific treatment or condition
while other group does not and they are called the _____
Treatment group, control
group.
