MATH 321 Lecture Notes - Lecture 8: Statistical Unit, Blind Experiment, Response Bias
30 Jun 2019
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Section 1.5
Bias-the results of the sample are not representative of the population.
Sampling Bias-the technique used to obtain the sample individuals tends to favor one part of
the population over another.
Sampling bias-can also occur with under coverage.
Nonresponse bias-when individuals selected to be in the sample do not respond.
Response bias-answers on a survey do not reflect the true feelings of the respondent.
Nonsampling errors-undercoverage, nonresponse biase, response bias, or data-entry error.
Sampling error-using a sample to estimate information about a population. This type of error
occurs because a sample gives incomplete information about a population.
1.6 The Design of Experiments
An experiment is a controlled study conducted to determine the effect varying one or more
explanatory variables or factors has on a response variable. Any combination of the value of the
factors is called a treatment.
Experimental Unit-is a person, object, or some other well defined item upon which a treatment
is applied.
A control group serves as a baseline treatment that can be used to compare it to other
treatments.
Placebo is an innocuous medication that looks, tastes, and smells like experimental medication.
Blinding refers to nondisclosure of the treatment the experimental unit is receiving.
Two types of blinding: Single Blinding and Double Blinding
Single blind experiments, the experimental unit (or subject) does not know which treatment he
or she is receiving.
Double blind experiments, neither the experimental unit nor the researcher in contact with the
experimental unit knows which treatment the experimental unit is receiving.
To design an experiment means to describe the overall plan in conducting the experiment.
A completely randomized design is one in which each experimental unit is randomly assigned
to a treatment.
Document Summary
Bias-the results of the sample are not representative of the population. Sampling bias-the technique used to obtain the sample individuals tends to favor one part of the population over another. Nonresponse bias-when individuals selected to be in the sample do not respond. Response bias-answers on a survey do not reflect the true feelings of the respondent. Nonsampling errors-undercoverage, nonresponse biase, response bias, or data-entry error. Sampling error-using a sample to estimate information about a population. This type of error occurs because a sample gives incomplete information about a population. An experiment is a controlled study conducted to determine the effect varying one or more explanatory variables or factors has on a response variable. Any combination of the value of the factors is called a treatment. Experimental unit-is a person, object, or some other well defined item upon which a treatment is applied. A control group serves as a baseline treatment that can be used to compare it to other treatments.
