Stat 1222 Test 1 UNCC

The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 1600 randomly selected students; 451 had such jobs. The population of interest to the Department of Education is:

 

all college students who have a job off campus.

 

none of these answers.

 

all college students

 

all 1600 students surveyed.

 

the 451 students in the survey who have off-campus jobs.

all college students

Is weight in lb nominal, ordinal, interval, or ratio?

 

Ratio

 

Ordinal

 

Interval

 

Nominal

ratio

nominal

labels/categories

interval

numbers with no true zero

ratio

numbers with true zero

ordinal

ordered categories (ranking)

Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected.  Identify the population, sample, parameter, statistic, and variable in this problem.

thirty five open-heart patients who underwent surgery in the last year

sample

Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected.  Identify the population, sample, parameter, statistic, and variable in this problem.

average length of stay of all open-heart patients who underwent surgery in the last year

parameter

Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected.  Identify the population, sample, parameter, statistic, and variable in this problem.

length of hospital stay

variable

Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected.  Identify the population, sample, parameter, statistic, and variable in this problem.

all open-heart patients who underwent surgery in the last year

population

Managers at a hospital are interested in the length of stay (in days) of open-heart patients who underwent surgery within the last year. Thirty five open-heart surgery patients admitted to the hospital within the last year are selected.  Identify the population, sample, parameter, statistic, and variable in this problem.

average length of stay of the thirty five selected open-heart patients

statistic

A researcher wishes to estimate the average amount spent per person by visitors to a theme park. She takes a random sample of forty visitors and obtains an average of $28 per person. The population of interest is

 

$28 per person.

 

theme park researchers.

 

visitors to the theme park.

 

the amount of money spent per person.

 

the forty selected visitors.

visitors to the theme park.

quantitative discrete

can only take on a limited number of values (e.g., only whole numbers)

quantitative continuous

can take on any value and any value between two values (e.g., out to an infinite number of decimal places).

qualitative

data that is descriptive and depicts qualities or characteristics

cluster sampling

divide a population into clusters, such as districts or schools, and then randomly select some of these clusters as your sample

simple random

researcher randomly selects a subset of participants from a population

stratified sampling

researchers divide subjects into subgroups called strata based on characteristics that they share (10 random freshmen, sophomores,etc.)

systematic sampling

ordered sampling frame (every tenth person)

convenience sampling

easiest for the researcher to access (asking people in your class)

right skewed graph (mean ? median)

mean > median

Left skewed graph (mean ? median)

mean < median

bimodal graph

two peaks

uniform graph

no real peak, all level

Which of the following would NOT be an appropriate measure of central tendency when looking at incomes of a middle class neighborhood when one neighbor just sold their startup idea to Facebook for $1,000,000?

Mean

No other answer choice was an acceptable measure of central tendency

Median

All other answer choices are acceptable measures of central tendency

Mode

mean

what is the symbol for sample mean?

x̄

The square root of the ____(a)_____ is called the ____(b)_____ .

 

(a)         variance

(b)         standard deviation

 

(a)         mean

(b)         median

 

(a)         standard deviation

(b)         variance

 

(a)         median

(b)         mean

(a)         variance

(b)         standard deviation

median

the middle number in a sorted ascending or descending list of numbers

mode

number that occurs most

What is the symbol for sample standard deviation?

s (fancy s)

All of the following are measures of central tendency EXCEPT:

 

standard deviation

 

mode

 

mean

 

median

standard deviation

The 54th percentile in a large data set is 98.6. Approximately what percentage of the observations are greater than 98.6?

 

50%

 

98.6%

 

54%

 

46%

 

1.4%

46%

The score made by a particular student on a national standardized exam is the 65th percentile. This means that 

 

His score is 65% of the average score.

 

About 65% of all scores on the exam were higher than his.

 

About 65% of all scores on the exam were lower than his.

 

His score is the 65th best on the exam.

 

He got about 65% of the answers correct.

About 65% of all scores on the exam were lower than his.

negative z-score

lower than mean

positive z-score

higher than mean

z-score equaiton =

(n - mean) / standard deviation (n is number in problem)

A researcher wants to determine the average income of the employed people of Omaha, Nebraska. He found that there are 385,600 employed people in the state. A group of 1,200 people are selected randomly to ascertain the income of each of those individuals. He finds that the average income of those 1,200 numbers to be $42,827. Identify the population in this context.

385,600 – 1,200 constitute the population

1,200 people selected for the study

385,600 employed people in Omaha

Average income of $42,827

385,600 + 1,200 constitute the population

385,600 employed people in Omaha

What is the symbol for population variance?

σ^2

When is the mode most useful?

Never

Categorical data

Numerical data

Numerical data when significant outliers are present

Categorical data

Mean, median, and mode are all measures of the ____ of a data set, while variance and standard deviation measure the ____ of a data set.

center, spread

Which of the following statistics is least impacted by outliers?

Mode

Mean

Range

Median

Variance

median