stats exam
What is descriptive statistics?
methods of organizing, summarizing, and presenting data in an informative way
What is inferential statistics?
methods used to estimate a population parameter based on a sample
The dispersion of data is also called
variation or spread
Which of the following variables would be best suited for a contingency table
Favorite color and gender
Continuous variables
Temperature in Orlando Amount of milk in a cup Height of carpet
Mutually exclusive classes
The classes don't overlap
What are examples of inferential statistics?
sampling distribution estimation of parameters hypothesis testing t-statistic
What are the reasons to study the dispersion of data?
Any small value for dispersion indicates that the data is closely clustered around the center It allows us to compare the spread in two or more distributions
A scatter diagram requires that both of the variables be what kind of data?
At least interval level
Methods for descriptive statistics
Calculating summary measures like the average Constructing a frequency distribution Constructing charts and graphs
Attributes of a discrete quantitative variable
Can assume only certain values in a range It can be used to count items, in which case it can only have integer values There are gaps between the values of this variable
What is an advantage of a cumulative frequency polygon over a histogram or a frequency polygon
It can show the total number of observations less than the particular class' upper limit
What does a small value for a measure of dispersion tell us about a set of data
It indicates that the data is closely clustered around the center
Of the following, which is one advantage of the standard deviation over the variance
It is in the same units as the data
Chebyshev's Theorem states that the proportion of values is at least 1-1/k^2, what is the meaning of K?
K is the number of standard deviations, greater than 1, within which that proportion of observations will be found
In using the "2 to the K rule" to determine the number of classes for a frequency distribution, what is the meaning of the variable K?
K is the smallest number of classes such that 2^k is greater than the number of observations
You can use a frequency table for
Majors of students Genders of students State of residence of students
Which of the following is true regarding medians and means
Medians can be calculated from ordinal level data, means cannot
What are the weaknesses of using range to measure dispersion
Might be skewed by a large variable Might be skewed by a small variable Only two values from the data are used
"Movie ratings" are
Ordinal
Proper and ethical behavior for a statistician?
Present his conclusions with clarity and integrity Remove outliers that bias the data too far in one direction
What level of data gives you the most information about the observation?
Ratio
Example of something on the interval level?
Shoe size
Which of the following is classified as ordinal level data?
Someone's ranking of their three favorite foods
Property of ordinal-level data
The data can be ranked or counted
A relative frequency distribution shows
The fraction or percentage of observations in each class interval
What is not part of a histogram?
The frequency of occurrence of a nominal variable
In the formula for calculating the mean of grouped data the M stands for
The midpoint of a given class
In the formula for calculating the mean of grouped data, M stands for
The midpoint of a given class
What is true regarding relative frequency distributions
The relative frequency is found by dividing the class frequencies by the total number of observations
What is a following of a relative frequency distribution
The sum of the relative frequencies must be one (provided no rounding errors)
Given the following weights in ounces of four apples which of the following is true
The variance would be in ounces squared
What are properties of ratio-level data?
The zero point of the data is meaningful The ratio between two measures is meaningful It has all the properties of interval-level data
Collective exhaustive classes
There is a class for each observation
Important properties of the arithmetic mean?
There is only one mean for a set of data All of the values in the data are used in calculating the mean The sum of the deviations is zero
Attributes of a continuous quantitative variable
Typically the result of measuring something No required gaps between values It can take on any value within a range of values
What is used to measure dispersion?
Variance Standard Deviation Range
How has technology increased the need for statistical analysis?
Vast amount of data are collected and interpreting it requires statistical knowledge.
A statistic is:
a characteristic of a sample
All of the automobiles sold in Canada in 2016 is
a population in the statistical sense
Steps of constructing a frequency distribution
1. Decide on the number of classes 2. Determine class width 3. Set individual class limits 4. Tally the number of observations in each class
What is the variance of the following population data? 2, 0, 1, 9
12.50
What is the standard deviation of the following sample data? 7, 6, 0, 2, 5
2.92
How does statistics help us understand large amounts of numerical information?
A good working knowledge of statistics is useful to organize and summarize information
What is the best definition of a statistical sample?
A portion, or part of the population of interest.
The value shown on the vertical axis of a cumulative frequency polygon for a particular class is found by
counting the number of observations less than the upper limit of the class
The two categories of statistical study are
descriptive and inferential
What are the two types of quantitative variables?
discrete and continuous
