2.1 organizing data Flashcards
raw data
data collected in original form
frequency distribution
organization of raw data in table form, using classes & frequencies
class
vale’s placed into a quantitative (measurement/ counting)or qualitative (characteristics) category
frequency
number of data values contained in a specific class
class limit
27-35, 36-44,etc
categorical frequency distribution
data that can be placed in specific categories nominal (categories (no ordering or direction) ) or ordinal (ordered categories)
formula for percentage
% = f/n x 100
f - frequency
n - #=of values total
grouped frequency distribution
data being is large, must be grouped into classes
lower class limit
58 - 64, 58 is the lowest
upper class limit
58 - 64, 64 upper limit
class boundaries
used to separate the classes so there are no gaps in the frequency distribution
Example: gap between 64 and 65
class width
subtract lower (or upper) class limit of one class from the lower (or upper) class limit of the next class
Example: 45 46 47 48 49 50 48 - 46 = 2 50 - 48 = 2 width = 2
class midpoint
numeric location of the center of the class
lower + upper boundary/ 2 = Xm
or
lower limit + upper limit/ 2 = Xm
frequency distribution must be mutually exclusive (overlapping)
Example:
10 - 20
20 - 30
30 - 40
if someone who was 30, which category would they be placed in. THEY CANT
Example correct way: 20 -30
31 - 41
42 - 52
Rules for constructing frequency distribution
- between 5 and 20 classes
- class width be odd numbers (not necessarily
- non overlapping
- must be continuous
- classes to accommodate all data
- classes must be equal in width
