The Steps Involved in Descriptive Statistics:
1. Decide on the number of classes/categories
a. For this problem use 6 classes.
b. Make sure the Class Width is accurate.
2. Calculate the Minimum Class Width
a. (High value-low value)/# classes and Minimum i
Other Important Terms for Statistics
Sample a subset of a population
Everything we DO count and measure
Why only a sample?
Parameter a number that describes a population characteristic (e.g. Average age of all the
college students in the United States)
Probability experiment an action through which counts, measurements or actions
Sample space the set of all possible outcomes
Event a subset of the sample space
Outcome the result of a single trial
CHOOSE A STUDENT
Assigning Event Probabilities
a priori Classical Method
Empirical Classical Method
Types of Probability
Classical (Equally Probable Outcomes)
Number of outcomes in event E
Number of outcomes in sample space
Each member of the population has the same likelihood of being selected
Set up a table at the mall & solicit responses
Set up a table at the Student Union & solicit responses
Types of Sampling
Simple Random Sample - Assign each m
The probability an event B will occur, given (on the condition) that another event A
We write this as P(B|A) and say probability of B, given A
Calculate the probability a student chosen at random (from the 586) is lef
Deciles (of which there are nine) and Percentiles (of which there are ninety nine) divide the data
into ten and one hundred parts respectively. Excel will calculate percentiles
Measures of Variation
Range =Max Value Min Value
o If only
If a sample size of n is desired from a population containing N elements, we sample one
element for every N/n elements in the population.
We randomly select one of the first N/n elements from the population list.
We then select every N
Sample Standard Deviation
o To calculate a sample variance divide the sum of squares by n-1.
o The sample standard deviation, s is found by taking the square root of the sample
o Samples only contain a portion of the population. This portion is
Sample Space Examples:
Describes the sample space
o Example: 2 dice are rolled
A picture of the sample space
o Example: Number of men and women in an eight person set
Two dice are rolled. Describe the sample space.