13. data analysis Flashcards
measure of central tendency
a mathematical way to find a midpoint or average score from a data set (using mean, mode, or median)
mean
statistical average - add up all the data points and divide by the number of scores in the data set
can be used with quantitative data, from linear data
sum -------------------------------- total number of values
median
central value of set of data - put data in rank order and find middle score. if even number of points, add middle 2 together and divide by 2
can only be used with quantitative data from linear scales
(middle value)
mode
the most frequent occuring data point
can be used with quantitative and qualitative data sets
(most common value)
measure of spread (aka measure of dispersion)
a mathematical way to describe the amount of variation between data points in a set
range
find the smallest value in the data set, subtract from the largest value
(largest value - smallest value)
outlier
a data point that differs significantly from other data points in the set
standard deviation
a value showing avg spread of data points from mean
bar chart
used when data is in different categories (discrete) (not a continuous scale) - that’s why there are gaps between the columns because the columns are not related in a linear way, not a continuous scale
data for DV goes on the Y, levels of IV go on X
bars represent totals, frequencies, etc
histogram
can be used when data is continuous (the bars are touching) (can be measured on an infinite scale) eg, time.
frequency of DV goes on Y, DV on X
data is grouped in intervals, eg, if the DV is age, it could be 0-5, 6-10, 11-15 etc
scatter graph
shows relationship between 2 co-variables
each point represents the point where ppts data points on the 2 co-variables meet
