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Business Stats Test 1
Terms in this set (85)
Collection of persons, objects, or items of interest
When researchers gather data from the whole population
Portion of the whole, and, if properly taken, is representative of the whole
Using data gathered on a group to describe or reach conclusions about that same group
Anything you draw from a sample
Descriptive measure of a population
Descriptive measure of a sample
Statistical analysis always starts with a _
Combining samples and descriptive statistics to draw conclusions about a population, like what its parameters are most likely to be
Parameters are _ and _ characteristics of a population. Each one is a _ number, so it _ change.
Examples of parameters
Mean of a pop
st dev (o)
Descriptive statistics are computed from _, so we know what they are. They are _ _ #s, but are _ _, which means they are different across all samples taken from the same population.
Examples of descriptive statistics
Mean (x bar)
st dev (s)
Lowest level of data measurement, used only to classify or categorize
Second highest level of data measurement, used to classify/categorize and to rank or order people/objects
Nominal and ordinal data
Derived from imprecise measurements
Can't use parametric statistics (nonparametric)
Next to highest level of data
The distances between consecutive numbers have meaning
Data are always numerical
Distances between numbers have meaning, data is numerical
Ratio of two numbers is meaningful
Data has absolute zero
An absolute zero in ratio data represents...
an absence of the characteristic being studied
Usually gathered by precise measurements
Ratio and interval
Can use parametric statistics
Mutually exclusive means...
The classes don't overlap
Events that don't happen at the same time
What is frequency?
How many items fall in each class
What is relative frequency?
Number of items in each class relative to the total
For almost all problems, probabilites are _ based on the ratio _, therefore they are for the most part _ _ and correspond to _ under distributions
Interest/all possible outcomes
Binomials, poissons, normals, and ts, are all equations that represent _ _ distributions and allow you to compute _
A summary of data presented in the form of class intervals and frequencies
When constructing a frequency distribution, the first step is to find the _. Then you organize the data into _, about 5-15. Then you determine the _ _.
Midpoint of each class interval
Value halfway across the class interval
Average of the two class endpoints
The proportion of the total frequency that is in any given class interval in a frequency distribution
Running total of frequencies through the classes of a frequency distribution
How to calculate cumulative frequency
Add each frequency to the one before it
What are five variables that might help a manager in doing his job?
Size of sale per customer
Number of employees working/day
Inventory turnover rate
Number of customers that enter the store per hour
Percentage of people paying with cash
What are four variables that might affect a restuarant?
Size of bill or tab
Percentage of capacity filled
Length of stay
Number of arrivals per 5 minute intervals
The time required to produce each tire on an assembly line
Number of quarts of milk a family drinks per month
Ranking the machines in your plant
The area code of US clients
The age of your employees
Dollar sales at the pizza shop per month
An employee's ID number
Response time of an emergency unit
Most frequently occuring value in a set of data
Median value in an ordered array of numbers
Measures of location define the _ value in a group
The _ is the generally the _ measure of typical value
Uses all the _ values but is affected by _ values and cannot be computed when a distribution is _
Median is the _ value. It marks _ in the group, so half the values are _ _ the median and half the values are _ _ the median
always greater than
always less than
Before we can find the median, we must first _ the values
The value of the median is _ affected by extreme values. The median _ _ found for open ended distributions but the median does _ utilize all the individual values
Mean is affected by_, so very high values _ and very small values _. Median is _ affected by outliers.
Pull it up
Pull it down
No matter what, median will always divide the sample in _ if the numbers are _. Mean will do this if the distribution is _.
If the distribution is open-ended, _ can't be computed. The median can only be computed if _
The middle number is known
A good measure of variation should be a _ number, use all the _ we have, have a point of _ that is usually the mean, enable us to make _ statements
Formula for mean
Add up all numbers and divide by the total
Measures of variability describe the _ or _ of a set of data
Formula for range
Range is a _ number but it does _ use all values
Take each number minus the mean
Square each result
Add the results
Divide by the total numbers-1
Variance units are always in _ of regular unit, so to simplify things we should put it in _
Standard deviation formula
Square root of variance
Standard deviation is the only one that can make _
Variance and standard deviation tell us how far away from or how close the _ our values are in general. That is, they tell us how _ or how _ our individual values are from each other.
Therefore, the closer/more similar the values are to each other and to their mean, the _ the variance and st dev
Variance ans standard dev would be zero when all the numbers are the _
Why are variance and st dev always either positive or zero?
Computed from squared numbers
The closer the mean and median are, the more _ the distribution is.
Subtracting the mean from each value of data yields the _
Deviation from the mean
Mean Absolute Deviation
Average of the absolute values of the deviations around the mean for a set of numbers
Take absolute value of deviations from the mean
Add them up
Divide by total number
The right half is a mirror image of the left half
A distribution that lacks symmetry
Positive skewed is when the tail goes to the _
Negative skewed is when the tail goes to the _
Perfectly symmetrical distributions have a skew of _
The occurance of one event does not affect the occurance of another event
We test the _ hypothesis and try to prove it.
States that the old theory is still true and our new idea is wrong
No equal sign ever!
New theory is true
P value is...
The smallest value of alpha for which the null hypothesis can be rejected
Discrete random variables are...
The set of all possible values is at most a finite or a countably infinite number of possible values
Continuous random variables are..
every value at every point over a given interval
The standard error of the mean is...
The st dev of the statistic of interest
Formula for coefficient of variation
St dev / mean
What is different about the formulas for SAMPLE variance and st dev?
When its a sample, you divide by n-1
Recommended textbook explanations
Elementary Statistics: A Step By Step Approach
Allan G. Bluman
Mario F. Triola
Understanding Basic Statistics
Charles Henry Brase, Corrinne Pellillo Brase
Elementary Statistics: A Step-by-Step Approach, with Formula Card
Allan G. Bluman
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