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31 Cards in this Set
- Front
- Back
Population |
The entire collection of individuals or objects you want to learn about |
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Sample |
Part of the population that is selected for study |
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Observational study |
Person carrying out the study does not control who or what is in the population |
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Population characteristic or parameter |
Number that describes an entire population |
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Sample size |
Number that describes a sample |
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Simple random sample |
Sample collected from a population in such a way that every different possible sample has n has an equal chance of being selected |
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Selection bias |
When the sample systematically and excludes some part of the population of Interest |
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Measurement bias |
When method of observation tends to produce values that differ from the True Values |
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Non response bias |
Responses are not obtained from all individuals selected |
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Variable |
Any characteristic who is Valium a chain from one individual to another |
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Data |
Result for making observations either on a single variable or simultaneously on two or more variables |
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Univeriable |
A data set consisting of observations on a single characteristic |
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Numerical data is |
Quantitative |
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Categorical data is |
Qualitative |
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Discrete variable |
If the possible values correspond to isolated points on a number line example whole numbers |
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Continuous variables |
If the value can be measured in many different ways that it can go on forever |
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Frequency |
Number of times a category appears in a data set |
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Relative frequency equation |
Frequency ÷ # of observations |
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Scatterplot |
Shows relationship between two or more variables |
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Time-series plot |
Graph of data collected over time that can help you see interesting Trends or patterns |
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Measure of center |
Describe where the data distribution is located along a number line. A measure of center provides info about what is typical |
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Measure of spread |
Describe how much variability there is in a data distribution. A measure of spread provides information about how much individual values tend to differ from one another |
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If the data distribution is approximately symmetric use |
Mean and standard deviation |
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If the shape of the data distribution is skewed or has outliers use |
median and interquartile range |
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Sample mean= |
Sum of x ÷ # of values |
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Population mean |
Average of every member of the population only if you have a census of the population |
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Sample variance= |
Sum of all variables × (variable-mean)÷ # of variable - 1 |
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Sample standard deviation= |
Avg distance from the mean Square root of s squared |
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Population variance= |
Sum of variables × (variable-mean) squared ÷ size of population |
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Outlier |
Any data point that is less than the lower quartile - 1.5×IQR. Any data point greater than upper quartile + 1.5×IQR |
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Z-score |
How many standard deviations the data value is from the mean Variable - mean ÷ standard deviation |