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Sampling Design
Identifying the optimal sampling design - the one
that minimizes sampling error and costs -- is the
goal of any good applied research project.
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Statistical Analysis and Modeling Services
At FPi, we have extensive,
wide-ranging experience in standard and advanced
analytical procedures, and can handle any size
statistical problem, from simple cross-tabulations,
to linear regressions, and more complex structure
equation models, |
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FPi
Statistical Consulting Services offers clients a one-stop place for
study design, sampling schemes, and statistical analysis and modeling.
Study Design: FPi
will develop or review existing study parameters to assure information
that is collected meets an identified sent of goals and objectives, and
cost parameters. Specific design issues that we have investigated
include appropriate data collection methodologies, sample size,
questionnaire design, question scales, screening criteria, questionnaire
length, incidences and costs, among money other design issues. We are
also experts on issues surrounding sampling balancing and data weighting
having conducted thousands of research studies.
Sampling Design:
Which is the best sampling approach and what sample size would be
optimal, balancing margin of error and costs? There are typically
numerous sampling procedures that can be employed to collected public
opinion and marketing research information. Random sampling, stratified
sampling, and cluster sampling are just a few. Selecting the most
approached sampling design will assure that the sampling data is projectable to the population of interest at the lowest possible error
and cost.
Different sample sizes
produce different margins of error. The calculations of sample sizes for
different sampling designs requires different formulas and choices. We
can do the mathematics, and help design sample size options that
maximize accuracy and minimize costs.
Statistical Analysis and
Modeling: Once data is collected it needs to be analyzed in ways that
produce actionable conclusions. At FPi, we have extensive, wide-ranging
experience in standard and advanced analytical procedures, and can
handle any size statistical problem. Examples of our analysis and
modeling capabilities are described below.
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Cross-Tabulations:
This is standard output in a public opinion and marketing research
study. It includes frequency and % responses to all questionnaire
items, and tables of the responses of key subgroups. We can
typically produce a set of standard cross-tabulation tables in less
than one day. Also outputted are standard data formats for more
advanced analysis, including Excel spreadsheets, SPSS and SAS data
formats.
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Correlation Analysis
and Linear Regression: Correlation analysis measures the
strength of a linear association between two question responses or
variables. In Linear Regression, the goal is to establish a correlation
relationship expressed in an equation. The equation can then be
used to predict the outcome of one variable, given changes in
another variable. When only one variable is used in the prediction,
it is called simple linear regression, and when more than one is used,
it is called multiple regression.
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Parametric and Non
Parametric Statistical Testing: There are many mathematical tests
that can be run to determine how related variables are to each
other. The most appropriate test is selected based on a number of
factors about the data type. Parametric statistical tests like
t-tests and F-tests are used when the data is normally distributed.
However, often data is not "normally" distributed. In this case a
special class of statistical tests, called nonparametric tests, must
be used. We will work with you to find the most appropriate test of
statistical significance given the circumstances of the data sets.
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Data Reduction:
Often you need to make sense of the patterns in the relationships
between variables in large data sets, or to reduce large data sets
into more manageable subsets, dimensions or factors. Doing this
requires techniques that identify the underlying statistical relationships between variables. Data
reduction techniques greatly simplify the description of large data
sets, and often help uncover latent associations between variables
and responses.
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Classifying
Respondents: Statistical procedures exist for grouping or
classifying the way people respond to questions. We statistically
model
how the responses of people are alike, and how they are different.
And, based on these response patterns, we develop unique subgroups of
people, each with their own opinions, behaviors and demographic
characteristics. This is an excellent way to identify different
segments in the population, and those that offer the best targets
for your product or service.
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Time Series Analysis:
The purpose of time series analysis is
to see how things change over a specified period. For instance, you
might want to test the affect of an advertising campaign over a
period of time, or compare the effects over time of one marketing
mix against another. We can measure and manage any kind of time
series data that you might have available. In the analysis, we can
provide diagnostic assessments, and build forecast models that will
help you estimate the effects of future actions based on the
patterns uncovered in actions you have taken in the past.
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Structural Equation
Modeling (SEM): The goal of a structural equation modeling
assignment is to help clients determine the extent to which
different theoretical models define a data set. The models can
describe simple associations between variables (such as in
regression or path analysis models), or more complex associations
and interactions between known variables and unknown or latent
constructs (as in confirmatory factor models). Our job is to define
the structure of different models, and test them, to see which
offers the best solution. Once we have identified the optimal model,
the associations and interactions are estimated to help understand how the variables are related
and which are critically important and need attention.
© 2005 Scott
W. Flexo, Ph.D. and Flexo & Partners, Inc. All Rights Reserved
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