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33 Cards in this Set
- Front
- Back
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univariate data sets
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one variable
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bivariate data sets (binary)
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two variables
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multivariate data sets
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more than two
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categorical data
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qualitative data , described by words
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numerical data
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quantitative data, numbers
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discrete
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variable with countable number of distinct values . 37
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continuous
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any value within an interval. physical measurements (lenght, width, time, speed), and financial variables (sales) 423.67
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observation
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subject: 1 person had this
1 2 3 4 or male female |
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variable
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charactristic of a subject or individual, such as employee income
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nominal data
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identitfy a category, same as qualitative, categorical, or classification data.
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ordical data
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natural order of something. rankuing of data values. usually code nominal data numerically
1= strongly agree, 2= agree 3= disagree (likert scale) |
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Interval data
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Absensce of meaningful 0.distances. likert scale. Ex: temperature
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ratio data
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meaningful 0 that represents the absence of the quantity being measured.
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Time series data
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the periodicity is the time between observation, can be annual, quarterly, monthy, weekly, daily.
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Cross sectional data
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if each observation represents a different individual unit (a person, firm, area) at the same point in time.
Variation among observations in relationships with other observations. |
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Central tendency
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where are the data values concentrated? what seem to be typical or middle data values?
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dispersion
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how much variation is there in the data? How spread out are the data values? are there unusual values?
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shape
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are the data values distributed symmetrically? skewed? sharply peaked? flat? bimodal?
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Frequency distribution
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a table formed by classifying n data values into k classes called bins.
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Sturges' Rule
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An equation to choose the number of bins needed. guideline proposed that says that everytime we double the sample size, we should add one bin.
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Sturges' Rule
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k= 1 + 3.3log(n)
n=sample size |
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Bin Limits
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Bin width = xmax- xmin / k
K is the number of bins needed |
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Histogram
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graphical rep of a frequency distribution.
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Modal class
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a histogram with a bar that is higher than those on either side
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Unimodal
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histogram with a single modal class
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Bimodal
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histogram with two modal class.
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Multimodal
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histogram with two or more modal classes.
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Symmertic
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In shape. If neither tale is longer than its symmetric
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Right-skewed
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positively skwed. histogram has a longer right taile, with most data values clustered on the let side.
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Left-skewed
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negatively skewed. histogram has a longer left tail, with most data values clustered on the right side.
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line chart
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display a time series, to spot trends, or to compare time periods. Used to display several variables at once. times series. time on x, numerical on y.
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scatter plot
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starting point for bivariate data analysis. invesitigate relationship between tow variables.
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law of large numbers
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as the number of trials increases, the empirical probabilty approaches its theoretical limit
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