module 3 Flashcards
1
Q
variable
A
- any measurable characteristic of an observational unit
- it can vary
2
Q
what are the three pieces of info for variables
A
- what the variable represents
- the measurement unit
- a description of the observation unit
3
Q
data for plural
A
datum
4
Q
central tendency
A
- typical value in your sample (mean)
- 2nd quartile
5
Q
dispersion
A
- spread of values (variance)
6
Q
how are categorical data catergorized
A
- counts (# of sampling units in each category)
- proportions (share of total sampling units in each category)
7
Q
______ and _______ indicate the central tendency of categorical data wheras _____ is used to indicate dispersion
A
counts and proportions, range
8
Q
what symbol is mean often given
A
Y with a line over top
9
Q
n=?
A
total number of observations/samples
10
Q
formula for mean
A
Y=variables/n
11
Q
how to calculate the variance
A
- calculate the mean
- calculate the difference between each data point and the mean, then square that answer
- sum the squares of the difference and divide by the number of observations/data points
-o^2=1/n(Yi-Y)^2 - each variable is subtracted by the mean the squared then divided by how many variables there are, then square rooted lol
12
Q
by dividing by the number of observations, we are calculating what is known as the ___________
A
population variance
13
Q
population vs sample variance
A
sample variance’s equation’s denominator is n-1 not just n
14
Q
steps to calculate quartiles
A
- sort the data from lowest to highest
- find the 2nd quartile by splitting data in half (if even number the 2nd quartile is the mean of the two middle numbers)
- find the first quartile (create subset of data, split bottom in half)
- find the 3rd quartile by repeating 3 but for upper half
15
Q
calculate interquartile range
A
-subtract 1st quartile from the 3rd quartile
