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18 Cards in this Set
- Front
- Back
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what is statistics?
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a science of data
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what is data?
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numbers with a context
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what are individuals?
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the objects described by a set of data
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what is a variable?
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any characteristic of an individual
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wjat os a categorical variable?
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takes numerical values for arithmetic operations such as adding averageraging make sense. The values of quantative variables are usually recorded in a unot of a measurement such seconds or kilograms
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what is exploratory data analysis?
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uses graphs and numerical summaries to describe the variables in a data set and the relations among them,.
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How do we explore data?
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begin by exmaining each varibale itself. begin with graphs
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what is the distribution of a veriable?
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tells us how often it takes these values of a categorical varable are labels of categories
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How do you find a mean?
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add the values of all the observations and divide by the number of observations
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what is a median?
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the midpoint of a distribution
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how do you find medians?
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(1) arrange all observations in order of size, from smallest to largest
(2) if the number of observations is oddd, the median M is the center observation in the ordered list. Find the location of the meidan by counting (n+1)/2 observations up from the bottom of the list. (3) if the number of the observation is even, the median M is the mean of the two center obserations in the ordered list. The location of the median is agains (n+1)/2 from the bottom of the list |
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how do you calculate quartarlies?
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(1) locate the medium
(2) Q1 is to the left of the median (3) Q3 is to the right |
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How do you calculate the IQR?
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IQR= Q3-Q1
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How do you find standard deviation?
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(X1-MEAN)+(X2-MEAN)+(X3-MEAN)
OVER N-1 TAKE SOLUTION DIVIDE BY N SQUARE ROOT THAT ANWSER |
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Approximately 68% of all observation lie between ______ of _________.
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the standard deviation
the mean |
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approx. 95% of observations fall between _____ of the ______.
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2(standard deviation)
of the mean |
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approx. 99.7 of observations fall between ________ of the _______.
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3(standard deviation) of the mean
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If x is an observation from a distribution that has mean and standard deviation, the standardized value of x (often called the z-score) is what?
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z= x-mean
over standard deviation |
