isds 2000 exam 1
in a study involving 949 elderly people, it was found that 22% of those who had depression went on to develop dementia, compared to only 17% of those who did not have depression 1. which of the following is true, more than one answer may be correct a. the sample consists of 949 elderly people b. the population is all elderly people c. the population is all younger people d. the sample consists of 949 younger people 2. are the numbers 22% and 17% associated with the population or the sample
a, b, sample statistics
numerical variables are a. qualitative b. quantitative
b
in which situation does surveying the entire population INSTEAD OF sampling just a part of the population make the most sense? a. a manufacturer of automobile tires wants to determine how long the tread of its tires last b. an owner of a chain of restaurants want to determine whether customers prefer seafood or meat entrees c. a teacher who has 30 students in her class wants to determine the avg. of the most recent test scores
c
relative frequency distributions are generally more useful than frequency distributions when a. comparing large data sets of the same size b. comparing small data sets of the same size c. comparing data sets of different sizes
c
which of the following best describes a frequency distribution for qualitative data? a. it groups data into histograms, and records the proportion b. it groups data into intervals called classes, and records the number of observations in each class c. it groups data into categories, and records the number of observations in each category
c
a bar graph is used for _______ data
categorical
a pie chart is used for _______ data
categorical
example: gender, political affiliation, city of birth, yes/no
categorical
frequency distribution is used for __________ data
categorical
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. colors of calls in a mall parking lot
categorical
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. racial composition of a high school classroom
categorical
ordinal scale of measure - categorical or numerical? - can or cannot be ordered? - is on the _______ scale because it can be categorized and ranked
categorical, can, ordinal
nominal scale of measure - categorical or numerical? - can or cannot be ordered?
categorical, cannot
histograms can be used to observe where the data seems to ________
cluster
data taken at one point in time
cross sectional
How does an ogive differ from a polygon? 1. an ogive is a graph of ____________ frequency distribution 2. a polygon is a graph of ___________ frequency distribution
cumulative (relative), relative
records the number of observations that falls below the upper limit of a particular interval - adding the frequency on each interval
cumulative frequency distribution
when a researcher examines quantitative data and wants to know the # of observations that fall below the upper limit of a particular class, the researcher is BEST served by creating a ________
cumulative frequency distribution
records the proportion of observations that falls below the upper limit of a particular interval - adding the relative frequency for each interval
cumulative relative frequency
describing or summarizing your data to explain the important characteristics - can summarize graphically, numerically - can create pie charts, histograms, line graph - calculating the mean, median, mode - example "76% of people are concerned"
descriptive statistics
what would you create if you had two categorical variables
either two pie charts or two histograms
when data is bell shaped, probabilities about the distance from the mean can be estimated using the __________
empirical rule
relative frequency equals
frequency / total
a _________ is a way to organize qualitative data into categories and record the number of observations in each category
frequency distribution
in order to summarize qualitative data, a useful tool is a _________
frequency distribution
____________ can be used to determine the shape of the data
histograms
methods use data from a sample population to make conclusions and decisions about the population
inferential statistics
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. a ski resort records the daily temperature during the month of january
interval
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. a sociologists notes the birth year of 50 people
interval
if a histogram is lower on the left, the data is _________ skewed
left
what are samples primarily used for
make inferences about population parameters
used to describe a typical value, the center, and where data seem to cluster
measures of center
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. a teacher marks whether each student is a boy or girl
nominal
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. the dean of the business school categorized students by major
nominal
a frequency polygon is used for ______ data
numerical
a histogram is used for ______ data
numerical
a stem and leaf diagram is used for ______ data
numerical
an ogive is used for ______ data
numerical
example: salary, revenue, expenses, amount spent
numerical
interval scale of measure - categorical or numerical? - can or cannot be ordered? - can or cannot be categorized? - can or cannot be ranked
numerical, can, can, can
ratio scale of measure - categorical or numerical? - can or cannot be ordered? - can or cannot be categorized? - can or cannot be ranked - has a true ______
numerical, can, can, can, zero
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. heights of 15 year olds
numerical, continuous
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. time it takes each student to complete a final exam
numerical, continuous
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. points scored in a football game
numerical, discrete
which of the following variables are categorical and which are numerical? if the variable is numerical, specify if it is discrete or continuous 1. the number of people who frequent a restaurant
numerical, discrete
what is the symbol for population standard deviation
o
what is the symbol for population variance
o^2
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. a restaurant surveys its customers about the quality of its waiting staff on a scale of 1 to 4, where 1 is poor and 4 is excellent
ordinal
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. analyst assigns a sample of bond issues to one of the following credit ratings, given in descending order of credit quality
ordinal
a summary measure that describes a characteristic of an entire population
parameter
population parameter is denoted by the symbol
pi
includes all observations for which conclusions are to be made
population
a relative frequency distribution for quantitative data identifies the
proportion of observations that occur in each class
________ are useful when comparing variables across data sets of different sizes
proportions
when constructing a histogram, what values/labels go on the x axis and the y axis 1. ___________ class limits on the x axis 2. _________________ or ___________ on the y axis
quantitative, frequency, relative frequency
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. a meteorologist records the amount of monthly rainfall over the past year
ratio
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. an investor collect data on the weekly closing price of gold throughout the year
ratio
in each scenario, select the appropriate scale of measurement (nominal, ordinal, interval, ratio) 1. an investor monitors the daily stock price of BP following the 2010 oil disaster
ratio
records the proportion of observations that fall into each interval (decimal)
relative frequency distribution
if a histogram is lower on the right, the data is ________ skewed
right
what is the symbol for sample standard deviation
s
what is the symbol for sample variance
s^2
a smaller subset of the population
sample
example: of all american adults, 1000 were surveyed
sample
what would you create if you had two numerical variables
scatterplot
formula for position of median
size of data set + 1 / 2
square root of variance
standard deviation
a summary measure that describes a characteristic of a sample
statistic
The process of using sample statistics to draw conclusions about true population parameters is called
statistical reference
a branch of applied mathematics which involves the collection, organization, analysis, interpretation, and presentation of data
statistics
an accounting professor wants to know the avg. GPA of the students enrolled in her class. she looks up info on blackboard about the students enrolled in her class and computes the avg. GPA of 3.29 1. the population is all students in the accounting class (true/false) 2. does the value 3.29 represent the population parameter or the sample statistic
true, population parameter
apple users complained of bad phone reception. a survey at a local store found that 2% of iphone 4 users had a reception problem. 1. the population is all iphone users (true/false) 2. does 2% denote the population parameter or the sample statistic
true, sample statistic
what is the symbol for population mean
u
a measure of variability that utilizes all data values and reflects how the observations vary or deviate from the mean
variance
what is the symbol for population size
N
categorical variables are a. qualitative b. quantitative
a
a summary measure that is computed to describe a characteristic of a sample taken from a population is called
a statistic
- approx ____% of observations are within one standard deviation of the mean - approx ____% of observations are within two standard deviations of the mean - approx ____% of observations are within three standard deviations of the mean
68, 95, 100
