Exam 1: ECN 221
Types of Data
Desen Pine! Nominal Ordinal
• No ranking alloud Ponting allowd
numerical data Interval
· Ranilang allowed . All chavecensics of
No WC O pointi ALWAVS numento
. can be sumenc .no measurable or non-imgic meaning to
manife! TYMCO paint
Zipcodes Mome ownership
credit scor 6 PA temperature INCOM € education level
Population USCA 2 CA cross sectionali vaines para ja
collected durdag cigie time period
Don't forget about the age old question of What does scientific development mean?
over a range of
sample Don't forget about the age old question of How do marginal costs and benefits relate to trade offs?
We also discuss several other topics like What is the difference between arithmetic and algebra?
Descriptive => Summarize
Inferential >> making statements
by examining sample
sample: o 22
Bel. Freq. Cum Rel. Freq. 0172/10 - 0:2 0:2 Don't forget about the age old question of What is legitimate political authority based on?
1110 On 0.220.1*0.3 2110 =0.2 0,3+ 0.2-0.5 12/10 +0.2 10.5*0,2 = 0.7
0.8 +0.25 1.0
'I = 10 We also discuss several other topics like How does axial stress vary from neutral axis?
Discrete Data : values that can bc COUNTED
les ex0,1,2,3. Children, vacation days continuas data: Balues that take on any real # Cincluding
decimal points We also discuss several other topics like What is the meaning of london forces in intermolecular interactions?
ex) time, weight class width: Solve for k=> 2 >n where K = of classes
n of data por est. class width: max volne- min value
example: 2 >n
2 > 10 K3.32 cround wp!)
class width: 5-0 =574= 1,25 rounded 2]
Measures of Central
there are shers
If the data Mode Categorcaj
the value that OCCUYS Most
* If not whole,
round wp* * when nis
Z-score? Z = X-X X
(mean = median
Left Creaviz median
Measures of Variability
Variance Lysample: st 6 (Xi-at
standard deviation Lsamples
Largest Valuea smallest value
b> Population -
Tu-38 / 20 / 4-0 uro a lot
Measures of Relative
Quartiles 1154-25** percengle () 4 and 50 percentile caz) L 3*75per cento de las)
where P= percentile
correlation Lx indicates strength
2 variables L ranges from - 1 Le correlation causation!
= E(x-7)(y 13(x-772&cy-jo
ramy ECX - ED cy - jo