Module 2

Question 1

To avoid ______ don’t perform these:
→ phrasing questions neutrally;
→ ensuring that the sampling method is appropriate for the demographic of the target population; and
→ pursuing high response rates.

Answer 1

biased results

Question 2

If a sample is sufficiently _____ and representative of the ______, the sample statistics, x and s, should be reasonably good estimates of the population parameters, μ and σ, respectively.

Answer 2

large; population

Question 3

The ___________ has a unique symmetrical shape whose center and width are determined by its mean and standard deviation respectively.

Answer 3

normal distribution

Question 4

Using the properties of the normal distribution, we can calculate a _________ associated with any range of
values.

Answer 4

probability

Question 5

Several ________ are helpful for estimating probabilities for a normal distribution.

Answer 5

rules of thumb

Question 6

About ___ of the probability is contained in the range reaching one standard deviation away from the
mean on either side, that is, P(μ-σ≤ x ≤μ+σ)≈ ____.

Answer 6

68%; 68%

Question 7

About ____ of the probability is contained in the range reaching two standard deviations (____ to be exact)
away from the mean on either side, that is, P(μ-2σ≤ x ≤μ+2σ)≈ ____.

Answer 7

95%; 1.96; 95%

Question 8

About ____ of the probability is contained in the range reaching three standard deviations away from the
mean on either side, that is, P(μ-3σ≤ x ≤μ+3σ)≈ ____.

Answer 8

99.7%; 99.7%

Question 9

A ______ of a point x is the distance x lies from the mean, measured in standard deviations, __ = (x - μ)/σ

Answer 9

z-value; z

Question 10

The ____________ states that if we take enough sufficiently large samples from any population, the
means of those samples will be normally distributed, regardless of the shape of the underlying population.

Answer 10

Central Limit Theorem

Question 11

The distribution of those sample’s means, called the _____________, more closely approximates a normal curve as we increase the number of samples and/or the sample size.

Answer 11

Distribution of Sample Means

Question 12

The ____ of any single sample lies on the normally distributed Distribution of Sample Means, so we can use the _____ curve’s special properties to draw conclusions from a single sample mean.

Answer 12

mean; normal

Question 13

What is μ?

Answer 13

Population Mean

Question 14

What is σ?

Answer 14

Population Standard Deviation

Question 15

What is x-bar?

Answer 15

Sample Mean

Question 16

What is s?

Answer 16

Sample Standard Deviation.

Question 17

The mean of the Distribution of Sample Means _____ the mean of the population distribution.

Answer 17

equals

Question 18

The standard deviation of the Distribution of Sample Means equals the standard deviation of the population distribution divided by the ______ of the sample size. Thus, increasing the sample size ______ the width of the Distribution of Sample Means.

Answer 18

square root; decreases

Question 19

Using the properties of the normal distribution and the Central Limit Theorem, we can construct a range around the sample mean, called a __________, to estimate the range in which the true ________ mean likely lies.

Answer 19

confidence interval; population

Question 20

The ____ of the confidence interval depends on the level of confidence, our best estimate of the population standard deviation, and the _____ size. We can only control the level of confidence and the sample size.

Answer 20

width; sample

Question 21

What is considered a large sample?

Answer 21

n is greater than or equal to 30

Question 22

For large samples (n≥30), the _____ and ______ bounds are calculated using the following equation: x-bar +or- z(s/SQRT(n))

Answer 22

lower; upper

Question 23

The function ___________ calculates the margin of error, which we add and subtract from the sample mean to find the confidence interval.

Answer 23

CONFIDENCE.NORM

Question 24

For _____ samples (n

Answer 24

small

Question 25

For small samples, we use a __________, which is shorter and wider than a normal distribution.

Answer 25

t-distribution

Question 26

The t-distribution provides a ____ range, a more conservative estimate of where the true population mean lies.

Answer 26

wider

Question 27

The function ___________ calculates the margin of error, which we add and subtract from the sample
mean to find the confidence interval.

Answer 27

CONFIDENCE.T

Question 28

We can also calculate confidence intervals for proportions. To do so, we must convert data to ___________.

Answer 28

dummy (0, 1) variables

Question 29

When estimating the ___________, we should ensure that the sample size is large enough by checking that both of the following conditions are true: n*p ≥ 5, and n(1−p)≥ 5. If either of these guidelines is not satisfied, we must collect a larger sample.

Answer 29

true population proportion

Question 30

What is the function for assigning a random ID# between 0 and 1 to each data point?

Answer 30

=RAND()

Question 31

=NORM.DIST(x, mean, standard_dev, cumulative)

• When cumulative is set to “TRUE”, NORM.DIST finds the ____________, that is, the probability of being less than or equal to the specified value x, for a normal distribution with the specified mean and standard deviation. (Inserting the value _______ provides the height of the normal distribution at the value x, which is not covered in this course.)

Answer 31

cumulative probability; “FALSE”

Question 32

=NORM.S.DIST(z, cumulative)

• When cumulative is set to “TRUE”, NORM.S.DIST finds the cumulative probability, that is, the probability of being ______ or _____ to the specified value z for a standard normal distribution.

Answer 32

less than or equal

Question 33

Which function returns the corresponding x-value on a normal distribution for the specified mean, standard deviation, and cumulative probability?

Answer 33

=NORM.INV(probability, mean, standard_dev)

Question 34

Which function returns the margin of error using a normal distribution for a specified alpha, standard_dev, and size? Alpha is the significance level, which equals one minus the confidence level (for example, a 95% confidence interval would correspond to the significance level 0.05).

Answer 34

=CONFIDENCE.NORM(alpha, standard_dev, size)

Question 35

Which function returns the margin of error using a t-distribution for a specified alpha, standard_dev, and size?

Answer 35

=CONFIDENCE.T(alpha, standard_dev, size)

Question 36

Which function returns value_if_true if the specified condition is met, and returns value_if_false if the condition is not met?

Answer 36

=IF(logical_test,[value_if_true],[value_if_false])

Question 37

Parameters are associated with ________, while Statistics are associated with _______.

Answer 37

Population; Sample