Business stats exam 1
Ordinal
Important because they tell you if you can use mathematics or not. Example: 1. Alabama 2.Stanford 3.Pennstate 4.Iowa. 4/2 doesn't mean the team is two times as better.
what is a property of ratio-level data?
The zero point of the data is meaningful, it has all the properties of interval-level data, the ratio between two measures is meaningful
Interval
Very unusual Ex: temperature. 80 Degrees F is not twice as hot as 40 Degrees. 0 Does not mean 0.
What are the two types of quantitative variable?
discrete and continuous
Relative Frequency
Frequency/n n=total number of observations
Community Frequency
Adding numbers from the frequency
Ratio
All math you do makes sense. Ex: 0 means you haven't been born yet. 20 is twice as old as 10.
Continuous
All numbers are accepted. Ex: How long to run a 100 meter dash? 8.4929 seconds?
Frequency
How many times a number occurs in a set of values
how to find the width of class intervals
(Max number in data-Min)/K This number will usually have to be plus or minus two to get the actual width
Descriptive statistics
Mean, Medium, mode. Dispersion
Inferential statistics
N=8500, Population Mx. Must be random. n=100, sample of the population. Sample mean is an x with a bar on top of it.
Community Relative Frequency
adding all of the RF numbers one by one.
distance students travel to class
ratio
nominal
Only for qualitative variables
what is a property of ordinal-level data?
The data can be ranked or counted
Discrete
all values between 2 possible values are NOT POSSIBLE ex: all # of children in family between 2 and 4. You can't have 2.5 children.
what represent data recorded at the nominal level
brand new purchased tv
Chebyshev theory
if the distribution is not symmetric (skewed)
The empirical rule
if the distribution is symmetric (bell shaped)
Student iq ratings
interval
Ux
mean of the N or population values
measures of location
mean, median, mode
a students state of birth
nominal
the jersey numbers of a sorority soccer team
nominal
Levels of measurement
nominal, ordinal, interval, ratio
K
number of class intervals. 2^k< or equal to total number of observations
a students academic class- that is, freshman sophomore etc
ordinal
number of hours student study per week
ratio
Levels of dispersion
the range, variance, standard deviation
whats the avg rate of return for .15, -.07, and .12?
[(1+.15)(1+-.07)(1+.12)]^1/3-1 1/3 because thats how many percents there were
suppose the us population grew from 300 million to 356 million from 1990 to 2014. at what rate did the us pop. grow on average per yer?
(ending #/beginning #)^1/24 - 1 ^1/24 bc thats how many years there were in between
Sample Variance Formula
(xi-mean)^2 x frequency add all of those up divide by / observations-1 square root it
RF of .40
40% of them took 20-30 mins to get to work. (this comes from class interval table)
CRF of .84
84% of workers took 40 mins or less to get to work
How does statistics help us understand large amounts of numerical information?
A good working knowledge of statistics is useful to organize and summarize information