Midterm 1 updated Flashcards
Metric Data refers to what?
Quantitative data
A cross tabulation is a process whereby …?
The frequency counts for two variables are displayed simultaneously
Numbers that are used to represent different grades (such as A, B, C, and D) that students get in a course represent which level of data?
Ordinal data
A quality control technician samples 25 cartons of cereal and weighs them to determine the number of ounces of cereal in each carton. The number of ounces in the cartons is an example of what level of data?
Ratio level
An effective method of obtaining an overview of data is what?
Data analysis
True or false: The sum of the relative frequencies of a grouped data set is always equal to one
True
Every hour, a quality control technician records the temperature (in degrees) in a laboratory. These temperatures are an example of what level of data?
interval level
True or false: a cumulative frequency distribution is also called an ogive
True
What is the activity or the process of collecting the data on the population called?
A census
When can nonparametric statistics be used?
When the data is nominal or ordinal
Our investigating company tracked all credit card purchases in 2010 and measured two variables: the type of credit card and the amount of dollars in each purchase. The data set presented represents what?
The population
In the pet food industry, buyers pre-buy the ingrediants for the up-coming year. One pet food company is looking to buy lamb for the lamb and rice flavour of their food. To do this they use data from the last several years and the estimated growth of their market in the coming year. What is this an example of?
Inferential statistics
Which of the following is NOT a dimension of big data?
Velocity
Variety
Veracity
Vacuolar
Vacuolar
True or False:
A frequency distribution shows how often each different value in a data set occurs
A histogram is the most commonly used graph to show frequency distributions
True and True
True or False:
1) Ratio data has known equal intervals
2) Interval data does not have a true or meaningful zero
1) False
2) True
True or False:
1) Cumulative frequency is used to determine the number of observations that lie above (or below) a particular value in a data set
2) Frequency polygons serve the same purpose as histograms, but are especially helpful for comparing sets of data
1) True
2) True
True or False:
1) Nominal data is data that can be labelled or classified into mutually exclusive categories within a variable
2) When you have paired numerical data. Scatter chart is a good option
1) True
2) True
True or False:
1) Pie charts become more effective if too many pieces of data are used
2) When negative data presents, Pie chart is a bad option
1) False
2) True
True or False:
1) Pie chart is a really good way to show relative sizes
2) A disadvantage of stem and leaf plots is they are only useful for small data sets from about 15 to 150 data points
1) True
2) True
If the standard deviation of a population is 9, what is the population variance and how did you find this?
81
It is 81 because the standard deviation is the square root of the variance; therefore, 9 is the squared root of 81
True or False:
The mode is the most frequently occurring value in a dataset
True
Quartiles divide data into how many subgroups?
4
If the shape of the distribution of a set of data is symmetric, the skewness is what?
zero
Mean absolute deviation, standard deviation, and variance are all measures of what?
Variability of a data set
For a set of data that are distributed in a bell shape, approximately what percentage of values will lie between the mean and two standard deviations?
95%
In the box and whisker plot, the length of the box is equal to what?
The inter-quartile range
True or False:
1) Cooling water below 0 degrees Celsius is an example of deterministic experiment
2) An event is a subset of a sample space
1) True
2) True
True or False:
1) The events “running forward” and “running backwards” are mutually exclusive
2) The empirical rule in statistics, also known as the 68-95-99.7
1) True
2) True
True or False:
1) A standard normal distribution has kurtosis of 3 and is recognized
2) Chebyshev’s theorem is used to the proportion of observations you would expect to find within a certain number of standard deviations from the mean
1) True
2) True
True or False:
1) The rule of thumb seems to be: If the skewness is between -0.5 and 0.5, the data are fairly symmetrical
2) Statisticians refer to the empirical rule as the two-sigma rule because nearly all observations occur within two standard deviations
1) True
2) True
If two events, Event A with probability P(A) and Event B with probability P(B) are mutually exclusive, then …?
P(A intersection B) = 0
Bayes’ rule is a formula for what?
Revising probabilities
If two events, Event A with probability P(A) and Event B with probability P(B) are independent, then the conditional probability P(A|B) is what?
P(A)
True or False:
If two events are independent, the joint probability of the two events is always equal to the product of the marginal probabilities of two events
True
If the occurrence or non-occurrence of one event does NOT affect the occurrence or non-occurrence of another event, the two events are what
Independent
The method of assigning probabilities based on the laws and rules pertaining to an experiment is called the .. ?
classical method
In any statistical experiment if the occurrence of one event precludes the occurrence of the other events, the events of the experiment are called what?
mutually exclusive events
If two events, Event A with probability P(A) and Event B with probability P(B) are independent, then
P(A intersection B) = P(A) x P(B)
Random variables, which are usually generated from experiments in which the observations or things are “counted” rather than “measured” are what
discrete random variables
One fair coin is tossed 20 times. Let X be the number of heads out of those 20 tossing experiments. What is the mean and variance of X?
10 and 5
Because 20 * .5 = 10 and 200.5(1-0.5) = 5
Suppose we have to randomly select 5 applicants from a pool of 24 applicants, 16 men, and 8 women. What is this selection an example of?
Hypergeometric distribution
True or False
In a distribution of a discrete random variable, X, the sum of the probabilities associated with the different possible values for X must always equal 1
True
Suppose we have to randomly select 5 applicants from a pool of 24 applicants, 16 men, and 8 women. What is this selection an example of?
Sampling without replacement
True or False?
- The time between successive arrivals of customers, Y, at a department store is an example of a continuous random variable
- In a binomial experiment, each trial results in one of two possible dependent outcomes
- True
- False
One of the main differences between the Poisson distribution and the binomial distribution is what?
Poisson distribution does not have a given number of trials like the binomial
What is the most common graphical approach to describe a discrete distribution?
Histogram
The random variable, “number of people who arrive at a store during a 15 minute interval” is an example of what?
Discrete random variable
