Quick Recap: Statistics Flashcards
Engineering Method
- Develop a clear description
- Identify the Important factors
- Conduct Experiments
- Propose or refine a model
- Manipulate the Model
- Confirm the Solution
- Conclusions and Recommendations
is the science of collecting, organizing, presenting, analyzing and interpreting numerical data to assist in making more effective decisions
statistics
is a collection of all possible individuals, objects, or measurement of interest
population
is a portion or part of the population of interest
sample
the total number of things in the sample
sample size
uses the data to provide descriptions of the population, either through numerical calculations or graphs or tables.
DESCRIPTIVE STATISTICS
makes inferences and predictions about a population based on a sample of data taken from the population in question.
INFERENTIAL STATISTICS
Types of Variables
- Qualitative/Categorical
- Quantitative/numerical
Variable with countable data
Discrete Variable
Types of Quantitative Variable
- Discrete
- Continuous
Measurable data, Intervals between whole numbers
Continuous Variable
result when a single variable is measured on an experimental unit.
Univariate Data
result when two variables are measured on a single experimental unit.
Bivariate data
result when more than two variables are measured
Multivariate data
General Types of Collecting Data
- Retrospective Study using Historical Data
- Observational Study
- Designed Experiments
This type of study strictly uses historical data, data taken over a specific period of time. In most cases, this type of study will be the least expensive. However, there are clear disadvantages:
(i) Validity and reliability of historical data are often in doubt.
(ii) If time is an important aspect of the structure of the data, there may be data missing.
(iii) There may be errors in collection of the data that are not known.
(iv) There is no control on the ranges of the measured variables (the factors in a study). Indeed, the ranges found in historical data may not be relevant current studies
RETROSPECTIVE STUDIES
Observing the process or the population, disturbing it as little as possible, and records the quantities of interest.
OBSERVATIONAL STUDIES
Deliberate or purposeful changes are made in the controllable variables in the system or process, observes the resulting system output data, and then makes inferences about which variables are responsible for the observed changes in output performance
DESIGNED EXPERIMENTS
