Stat exam 1 terms. – Flashcards
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Population
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The set of all elements of interest in a particular study. (2) The collection of all elements of interest.
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Parameter
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A numerical characteristic of a population, such as population mean μ, a population standard deviation σ, a population proportion p, and so on.
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Sample
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A subset of the population.
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Statistic
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A numerical characteristic of a Sample.
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Sample Size
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The number of units in your sample
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Census
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A survey to collect data on the entire population.
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Pie Chart
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A graphical device for presenting data summaries based on subdivision of a circle into sectors that correspond to the relative frequency for each class.
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Bar Chart
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A graphical device for depicting qualitative data that have been summarized in a frequency, relative frequency, or percent frequency distribution.
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Frequency Distribution
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A tabular summary of data showing the number (frequency) of data values in each of several nonoverlapping classes.
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Histogram
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A graphical presentation of a frequency distribution, relative frequency distribution, or percent frequency distribution of quantitative data constructed by placing the class intervals on the horizontal axis and the frequencies, relative frequencies, or percent frequencies on the vertical axis.
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Scatter Diagram
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A graphical presentation of the relationship between two quantitative variables. One variable is shown on the horizontal axis and the other variable is shown on the vertical axis. (2) A graph of bivariate data in which the independent variable is on the horizontal axis and the dependent variable is on the vertical axis.
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Time Series Plot
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A graphical presentation of the relationship between time and the time series variable. Time is shown on the horizontal axis and the time series values are shown on the vertical axis.
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Mean
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A measure of central location computed by summing the data values and dividing by the number of observations.
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Mode
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A measure of location, defined as the value that occurs with greatest frequency.
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Median
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A measure of central location provided by the value in the middle when the data are arranged in ascending order.
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Range
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A measure of variability, defined to be the largest value minus the smallest value.
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Standard Deviation
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1) A measure of variability computed by taking the positive square root of the variance. (2) The positive square root of the variance.
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Interquartile Range
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A measure of variability, defined to be the difference between the third and first quartiles.
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Variance
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(1) A measure of variability based on the squared deviations of the data values about the mean. (2) A measure of the variability, or dispersion, of a random variable.
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Quartile
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The 25th, 50th, and 75th percentiles, referred to as the first quartile, the second quartile (median), and third quartile, respectively. The quartiles can be used to divide a data set into four parts, with each part containing approximately 25% of the data.
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Box Plot
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A graphical summary of data based on a five-number summary.
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Correlation coefficient
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(1) A measure of linear association between two variables that takes on values between -1 and +1. Values near +1 indicate a strong positive linear relationship; values near -1 indicate a strong negative linear relationship; and values near zero indicate the lack of a linear relationship. (2) A measure of the strength of the linear relationship between two variables.
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Data Types
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Qualitative
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Non-numeric values that indicate something about a set data
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Quantitative
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Numeric values that indicate how much or how many of something. Quantitative data are obtained using either the interval or ratio scale of measurement.
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Nominal
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The scale of measurement for a variable when the data are labels or names used to identify an attribute of an element. Nominal data may be nonnumeric or numeric.
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Ordinal
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The scale of measurement for a variable if the data exhibit the properties of nominal data and the order or rank of the data is meaningful. Ordinal data may be nonnumeric or numeric.
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Discrete
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random variable that may assume either a finite number of values or an infinite sequence of values.
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Continuous
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A random variable that may assume any numerical value in an interval or collection of intervals.
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Cross-sectional
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Data collected at the same or approximately the same point in time.
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Empirical Rule
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A rule that can be used to compute the percentage of data values that must be within one, two, and three standard deviations of the mean for data that exhibit a bell-shaped distribution.
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Chebyshev's rule
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A theorem that can be used to make statements about the proportion of data values that must be within a specified number of standard deviations of the mean.
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z-score
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A value computed by dividing the deviation about the mean (xi -) by the standard deviation s. A z-score is referred to as a standardized value and denotes the number of standard deviations xi is from the mean.
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Percentile
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A value such that at least p percent of the observations are less than or equal to this value and at least (100 - p) percent of the observations are greater than or equal to this value. The 50th percentile is the median.
