Studied by 26 peopledata set
a collection of data values
data value or datum
Each value in the data set is called a __ or a _______
data
facts, figures and information collected on some characteristics of a population or sample
qualitative or quantitative data
Data can be classified as
Population
refers to the totality of objects, persons, places, things used in a particular study.
Sample
any subset of population or few members of a population
investigator
The person who plans and conducts the statistical investigation independently or with the help of others
respondent
The person who answers/responds to the set of questions
enumerator
The person who collects data by conducting an enquiry or an investigation
Categorical data
A type of data that is used to group information with similar characteristics, also called qualitative data
numerical data
A type of data that expresses information in the form of numbers, also called quantitative data
Nominal Scale
classifies data into mutually exclusive (non-overlapping), exhausting categories in which no order or ranking can be imposed on the data
Ordinal Scale
classifies data into categories that can be ranked; however, precise differences between the ranks do not exist.
Interval Scale
ranks data, and precise differences between units of measure do exist; however, there is no meaningful zero.
Rational Scale
possesses all the characteristics of an interval measurement, and there exist a true zero
Primary data
is collected firsthand by a researcher (organization, person, authority, agency or party etc) through experiments, surveys, questionnaires, focus groups, conducting interviews and taking (required) measurements.
Secondary data
is readily available (collected by someone else) and is available to the public through publications, journals and newspapers.
Variable
is a measure or characteristic or property of a population or sample that may have a number of different values.
Variable
It is the characteristic or property that is measured, controlled, or manipulated in research.
Constant
is a characteristic or property of a population or sample which is common to all members of the group.
Retrospective
cohort studies are a type of observational research in which the investigator looks back in time at archived or self-report data.
Observational studies
process or population is observed and disturbed as little as possible, and the quantities of interests are recorded.
Design of experiments
is defined as a branch of applied statistics that deals with planning, conducting, analyzing, and interpreting controlled tests to evaluate the factors that control the value of a parameter or group of parameters.
Retrospective
Observational studies
Design of Experiments
The three basic methods of collecting data
Sampling
The process of selecting just a small group of cases from out of a large group
Impracticable
Budget
Time
needed quickly
WHY THERE IS A NEED TO SAMPLE?
n=N/(1+Ne^2)
Slovin’s Formula
Andrew fisher formula
(1+CL)/2
Confidence level to Z-score Formula
Probabilistic Sampling
In every element of our sample the probability of them has the same weight. EPS (Equal Probability of Sampling)
Stratified Sampling
a method of sampling that involves the division of a population into smaller sub-groups known as strata.
Random Sampling
a subset of a statistical population in which each member of the subset has an equal probability of being chosen. Meant to be an unbiased representation of a group.
Systematic Sampling
a type of probability sampling method in which sample members from a larger population are selected according to a random starting point but with a fixed, periodic interval
Cluster Sampling
a probability sampling technique where researchers divide the population into multiple groups for research. Researchers then select random groups with a simple random or systematic random sampling technique for data collection and data analysis.
Non-Probabilistic Sampling
also called judgment or subjective sampling. This method is convenient and economical but the inferences made based on the findings are not so reliable
Convenience Sampling
taken from a group of people easy to contact or to reach. For a example, standing at a mall or a grocery store and asking people to answer questions.
Purposive Sampling
also known as judgmental, selective, or subjective sampling, is a form of non-probability sampling in which researchers rely on their own judgement
Quota Sampling
a sampling methodology wherein data is collected from a homogenous group. You continue sampling for each cell until you get the desired number and then stop
Snowball Sampling
is a recruitment technique in which research participants are asked to assist researchers in identifying other potential subjects.
Probability
the likelihood or chance of an event occurring
E(number of ways achieving success)/S(total number)
Probability Formula
Experiment
used to describe any process that generates a set of data
Event
consists of a set of possible outcomes of a probability experiment. Can be one outcome (simple event) or more than one outcome (compound event)
Sample space
the set of all possible outcomes or results of a random experiment.
element
Each outcome in the sample space
Convenience Sampling
Purposive Sampling
Quota Sampling
Snowball Sampling
Non-Probabilistic Sampling
Stratified Sampling
Random Sampling
Systematic Sampling
Cluster Sampling
Probabilistic Sampling
Null space
a subset of the sample space that contains no elements and is denoted by the symbol Æ. It is also called empty space.
Intersection of Events ( A ∩ B)
the event containing all elements that are common to A and B
1. Mutually Exclusive Events ( A ∩ B = O/ )
they have no elements in common
Union of Events ( A ∪ B )
containing all the elements that belong to A or to B or to both
Compliment of an Event (A ∩ C)’
t A with respect to S is
the set of all elements of S that are not in A and is denoted by A’
Statistical Unit
the items on which measurements are taken
Note
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