Unit 1 Review Flashcards
quantitative variable
one that takes on a numerical value for a measured or counted quantity
categorical/qualitative variable
one of a limited, usually fixed, number of possible values
discrete variable
a quantitative variable that takes a fixed set of possible values with gaps between(e.g.: shoe size)
continuous variable
a quantitative variable that can take away any value in an interval on the number line(e.g.: temp)
frequency
the number of times a particular value or category occurs within a dataset
relative frequency
the proportion or % of times a value occurs out of the total number of observations
Distribution is unimodal if ___ and biomodal if ___.
it has a single peak; it has two distinct peaks
distribution is approx. symmetric if…
the freq tables are about the same for all values
basic parameters for describing distribution
context, shape(skew, uni vs bimodal), center(mean/median), variability(range, IQR or stdev) and outliers
median
midpoint of a distribution
The mean is __ than the median if the distribution has a right skew; The mean is __ than the median if the distribution has a left skew.
greater than; less than
IQR
the distance between the 1st and 3rd quartiles of a distribution(Q3-Q1)
1.5 x IQR rule for outliers
outliers < Q1 - (1.5*IQR); outliers > Q3 + (1.5 * IQR)
the median is __ to outliers, while the mean is not
resitant
The empirical rule
68% of the data falls within 1 stdev of the mean, 95% falls within 2 and 99.6% falls within 3.
The empirical rule equation(for approx. normal distributions)
mean +- stdev = interval
z-score equation
x-mean/stdev
