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