# Ch.1

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Data
Consists of information coming from observations, counts, measurements, or responses.
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Statistics
the science of collecting, organizing, analyzing, and interpreting data in order to make decisions.
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Two types of data sets?
Population, Sample
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Population
collections of all out comes, responses, measurements, or counts that are of interest.
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Sample
a subset, or part, of a population
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Parameter
a numerical description of a population characteristic
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statistic
a numerical description of a sample characteristic
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A sample statistic will not change from sample to sample True or False
The statement is false. A sample statistic can change from sample to sample. A parameter will not change*
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Descriptive statistics
the branch of statistics that involves the organization, summarization, and display of data.
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Inferential statistics
the branch of statistics that involves using a sample to draw conclusions about a population.
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Select all the levels of measurement for which data can be qualitative. A. Nominal .B. Interval C. Ratio D. Ordinal
Nominal Ordinal
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Data at the ordinal level are quantitative only. True or False
False. Data at the ordinal level can be qualitative or quantitative.
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For data at the intervalâ€‹ level, you cannot calculate meaningful differences between data entries True or False
The statement is false. A true statement isâ€‹ "For data at the intervalâ€‹ level, you can calculate meaningful differences between dataâ€‹ entries."
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More types of calculations can be performed with data at the nominal level than with data at the interval level True or False
False. More types of calculations can be performed with data at the interval level than with data at the nominal level.
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Data at the ratio level cannot be put in order.
The statement is false. A true statement isâ€‹ "Data at the ratio level can be placed in a meaningfulâ€‹ order."
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What is the difference between an observational study and anâ€‹ experiment?
In anâ€‹ experiment, a treatment is applied to part of a population and responses are observed. In an observationalâ€‹ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.
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What is the difference between a census and aâ€‹ sampling?
A census includes the entire population. A sampling includes only part of the population.
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What is the difference between a random sample and a simple randomâ€‹ sample?
With a randomâ€‹ sample, each individual has the same chance of being selected. With a simple randomâ€‹ sample, all samples of the same size have the same chance of being selected.
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What is replication in anâ€‹ experiment? Why is replicationâ€‹ important?
Replication is repetition of an experiment under the same or similar conditions. Replication is important because it enhances the validity of the results.
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A placebo is an actual treatment. True or False
The statement is false. A placebo is a fake treatment.
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Aâ€‹ double-blind experiment is used to increase the placebo effect. True or False
The statement is false. Double blinding is used to decrease the placebo effect.
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Using a systematic sample guarantees that members of each group within a population will be sampled. True or False
False. Using a stratified sample guarantees that members of each group within a population will be sampled.
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The method for selecting a stratified sample is to order a population in some way and then select members of the population at regular intervals. True or False
False. The method for selecting a systematic sample is to order a population in some way and then select members of the population at regular intervals.
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Observational studies are sometimes referred to as natural experiments. Explain what this means.
In an observationalâ€‹ study, a researcher measures characteristics of interest of a part of a population but does not change existing conditions.
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nominal level of measurment
qualitative only. Data at this level are categorized using names, labels, or qualities. No mathematical computations can be made at this level.
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Ordinal Level of measurment
Qualitative and quantitative. Data at this level can be arranged in order, or ranked, but differences between data entries are not meaningful.
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interval level of measurement
can be ordered, and meaning full differences between data entries can be calculated. No inherent zeros
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ratio level of measurment
can be ordered, and meaning full differences between data entries can be calculated. Has inherent zeros
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Blinding
a technique where the subjects do not know whether they are receiving a treatment or a placebo
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Double-blind experiment