lec 1 Flashcards
what is a categorical variable?
qualitative characteristics without a numeral scale.
what is the significance of a NOMINAL categorical variable?
the lack of an order or hierarchy.
what is the significance of an ORDINAL categorical variable?
the possesion of an order or hierarchy
what is a numerical variable?
a variable with quantitative characteristics, typically relative to a numerical scale.
A continuous numerical scale is significant because of what?
it utilities divisible units, e.g. body temperature can be 1.5 and not just 1 or 2.
a discrete numerical scale is significant because of what?
it utilizes indivisible unis, e.g. the rank of a competitor in the Olympics, 1st, 2nd, 3rd, so on.
what are discriptive statistics?
statistics that tell us something about the values in a sample
what are the different ‘average’ values?
mean, median, mode.
what is a mean?
the sum of all the numeric responses divided by the total number of responses.
what is a median?
the middle number in the line of data, e.g. 1,2,3,4,5 the median would be 3, not 5 (the mean)
what is the mode?
the most frequent observation, e.g. 1,2,2,2,3,4,4,5 the mode would be 2
what are the ways that an observation can differ?
range, variance, and standard deviation
what is ȳ ?
the mean
if the mean, median, and mode are insignificantly different that would be called what?
a bell-shaped normal distribution
what is variance?
the sum of how every observation differs from the mean, squared
what is standard deviation?
the square root of variance
what can standard deviation not be?
negative
standard deviation is in the same or different units than the observation?
the same
what is your coefficient of variation, or (CV)
standard deviation expressed as a percentage of the mean
what is the interquartile range?
the range of the inner 50% of the data
what kind of plot focuses on interquartile range?
a box plot
what are the rules for making effective graphs?
show the data, keep the message clear, represent magnitudes honestly, and draw graphical elements clearly.
what kind of graph utilizes a single categorical variable?
a bar graph
what kinds of graphs utilize a single numeric variable?
A histogram, and a cumulative frequency distribution.
what kind of graph utilizes a spacially significant variable?
maps
what kind of graph utilizes two categorical variables?
a grouped bar graph and a mosaic plot
what kind of graph utilizes two numeric variables?
a scatter plot and line graph
what kind of graphs utilize one categorical and one numeric variable?
a box pot, a violin plot, or a dot plot.
