Data and Variables Flashcards
Why is data collected?
To monitor variables
What is a variable?
A descriptor that can take different values
What are the 2 categorical variables?
Nominal and ordinal
What do you call named variables?
Nominal
What do you call ranked variables?
Ordinal
What are the 2 quantitative variables?
Ratio and interval
What are the characteristics of ratio variables?
Fixed distance between units AND fixed zero
What are the characteristics of interval variables?
Fixed distance between units BUT zero is not really zero
What are 2 examples of ratio data?
Height and number of beans
What are 2 examples of interval data?
Temperature and IQ score
What 2 formats can quantitative data alone be in?
Discrete or continuous
What do parameters describe?
Population variables
What is another word for central tendency?
Average
What are the 3 measures for central tendency?
Mean, median and mode
What are the 4 measures of variability?
Range, interquartile range, variance and standard deviation
What is range?
The spread of all the data
What is the interquartile range?
It contains the middle
50% of values, so from the 25th - 75th percentile
How do you calculate the 25th percentile?
0.25 x (N+1) = an xth value
How do you calculate the 75th percentile?
0.75 x (N+1) = an xth value
How do you calculate the IQR?
IQR = 75th percentile value — 25th percentile value
What is the relationship between variance and standard deviation?
Variance is standard deviation squared
What is variance?
A measure of how close a variable is to the mean
