A z-score transformation is a useful statistical tool because it enables statisticians to

1] If Madeline wanted to know whether or not her sample results could be generalized to the population, she would use ______ statistics. If she were summarizing the data from her sample, she would use ______ statistics.

Inhaltsverzeichnis Show

What does the z

		inferential; descriptive
		descriptive; inferential
		inferential; quantitative
		quantitative; descriptive

Professor Baker provided a set of in-depth instructional materials for half of the students (randomly determined) taking her experimental methods course. She then compared their test scores against those of the other half of the students who did not receive a set of instructional materials. What is the dependent variable in the study?

		the total number of students
		the test scores of the students
		whether or not students got a set of instructional materials
		the difficulty of the test

Dr. Trebeck is testing adults to determine the effects of 3 different music tempos on how quickly the adults are able to respond in a Jeopardy-style task. The independent variable in this study is ___________.

		different music tempos
		adults vs. children
		time of responding (i.e., how quickly they are able to respond)
		gender of the subjects

Identify the scale of measurement for eye color (blue, black, brown, green, etc.)

		Interval
		Ordinal
		Ratio
		Nominal

Identify the scale of measurement for the amount of money donated to charity in the previous tax year by one particular family.

		Nominal
		Ordinal
		Interval
		Ratio

Identify the scale of measurement for the rankings of the five top-winning horses in the Kentucky Derby (i.e., 1st place, 2nd place, 3rd place, 4th place, and 5th place).

		Nominal
		Ordinal
		Ratio
		Interval

Identify this variable as either measurement (quantitative) or categorical (qualitative):

Brand of microwave owned

		Measurement (quantitative)
		Categorical (qualitative)

Identify this variable as either measurement (quantitative) or categorical (qualitative):

Total daily intake of calories

		Measurement (quantitative)
		Categorical (qualitative)

Is this variable discrete or continuous?

Total time spent in sleep last night

Is this variable discrete or continuous?

Gender

"How many days per week do you sleep for a minimum of 8 hours per day? Circle Only One Number: 0 1 2 3 4 5 6 7"

This type of question is an example of ___________.

		a closed-ended question
		an open-ended question
		a meta analysis
		a factorial analysis

I am selecting people to call for jury duty. It's a small county, so I place the names of everyone who is eligible in a large hat. After mixing thoroughly, I draw 37 people to call. The sampling plan that I used is ________.

		systematic random sampling
		stratified sampling
		cluster sampling
		simple random sampling

Today, Angelica took a written test designed to measure her IQ level. Her IQ score today was 125. Last week, her IQ score on the same test was 72. This particular IQ test appears to lack _____________.

		reliability
		validity
		generalizability
		bias

What is the margin of error?

		the mistakes made by an experimenter during the sampling stage
		the mistakes made by a researcher during the experimental stage
		the overall measure of accuracy for an experiment
		the measure of accuracy of a sample survey or poll

A sample made up of volunteers may be biased because ______.

		the control group and the experimental group can never be equated (the margin of error is too great between the control group and the experimental group)
		using volunteers is often not economical
		volunteers may not be representative of the population
		the control group and the experimental group are too similar

The following type of survey question is an example of _______________.

"For this survey question, please write two sentences describing your first pet."

		an closed-ended survey question
		an open-ended survey question
		a common pitfall when asking survey questions
		an experiment that lacks reliability and validity

Difficulties -- as well as disasters -- can occur in sampling. Which of the following is NOT an example of either a difficulty or a disaster in sampling?

		using the wrong sampling frame
		not being able to contact the individuals who have been selected for the sample
		getting no response or getting a volunteer response
		all of the above are examples of either difficulties or disasters in sampling

Identify one of the seven pitfalls of conducting surveys for the following survey question:

"Shouldn't former drug dealers be allowed to not vote in elections if they didn't sell drugs to children and they were in prison for less than 25 years or they sold drugs to adults for more than 10 years, if they expressed remorse (or if they didn't express remorse)?

		Asking the uninformed
		Unnecessary complexity
		Ordering of questions
		Confidentiality and anonymity

Validity is best described as ___________________.

		a measurement that is systematically off the mark in one direction
		a measurement that is systematically off the mark in both directions
		a measurement that actually measures what it purports to measure
		a measurement that will give you the same consistent result time after time

Identify one of the seven pitfalls when conducting surveys for the following survey question: "Do you agree with the experimenter of this study that capital punishment should be outlawed?"

		Deliberate bias
		Confidentiality and anonymity
		Asking the uninformed
		Unnecessary complexity

Use the following set of SAMPLE data:

-2 -1 2 4 5 5

What is the standard deviation of this sample data set (i.e., the square root of the variance)?

		2.71
		2.79
		3.06
		9.37

Use the following set of SAMPLE data:

-2 -1 2 3 6 8

What is the mean of this data set? (rounded)

		3.67
		2.67
		-3.67
		3.17

Use the following set of SAMPLE data:

-2 -1 2 4 5 5

What is the median?

		2.00
		3.00
		3.50
		4.00

Use the following set of SAMPLE data:

-2 -1 2 4 6 9

What is the range?

		5
		7
		9
		11

Use the following set of SAMPLE data:

-2 -1 2 4 5 5

What is the Interquartile Range?

		3
		4
		6
		7

Construct a Stem and Leaf plot (stemplot) using the data below. The sum (total) of the numbers that comprise the leaf in the first row is ____:

11 25 22 19 23 21 17 27 21 21 23 28 10 29

		11
		17
		19
		29

Using the following data (which are sample exam scores), construct a Grouped Frequency Distribution on your scrap paper.

11 25 22 19 23 21 17 27 21 21 23 28 10 29

Intervals Real Limits Midpoint f cf r% c%

10 - 13

14 - 17

18 - 21

22 - 25

26 - 29

What score is associated with the 50th percentile?

		18 - 21
		19.5
		21.5
		23

Use the Grouped Frequency Distribution that you constructed on your scrap paper in the previous question to answer the following:

What percentage of people scored between (and including) 26 and 29?

		14.29%
		19.72%
		21.43%
		28.57%

Assume that verbal SAT scores constitute a normal distribution with a mean of 600 and a standard deviation of 100.

What SAT score corresponds to the 30.85th percentile?

		425
		450
		550
		600

Assume that verbal SAT scores constitute a normal distribution, with a mean of 500 and a standard deviation of 100.

What percentage of scores are between 535 and 625?

		46.88%
		36.32%
		32.36%
		25.76%

The scores on a PSY 1110 exam were negatively skewed. Jody scored the mean, Marcia scored the median, and Greg scored the mode. Who had the lowest score?

		Jody
		Marcia
		Greg
		All three had the same score

The Interquartile Range contains the middle-most _____________:

		1/4 of the cases
		1/2 of the cases
		3/4 of the cases
		9/10 of the cases

Which one of the following statements is false?

		The variance is the standard deviation squared, and the standard deviation is the square root of the variance.
		The variance can never be greater than the standard deviation.
		The variance is always a positive number, because it is derived by calculating the squared raw data values.
		The variance is a measurement of the spread between numbers in a data set. The variance measures how far each number in the set is from the mean.

The following defines the normal curve:

		The normal curve is always unimodal; it is never bi-modal.
		mean = median = mode (i.e., the mean, median, and mode are all approximately the same value)
		The normal curve is always symmetrical.
		all of the above

Transforming X values (i.e., raw data scores) into z-scores NEVER changes the shape of the distribution. True or false?

A positive z-score always corresponds to an X value (i.e., a raw data score) that is above the mean. True or false?

A z-score transformation is a useful statistical tool because it enables statisticians to _____:

		determine which scores are the best scores in a distribution
		compare two or more distributions' skewness
		more easily determine the highest and lowest scores in a distribution
		compare and interpret scores from virtually any distribution

Assume that the µ (population mean) for a test was 50 and the σ (population standard deviation) was 4.5. Lisa scored 56 on the test, Jill had a z-score of +1.5, and Ellianna scored at the 75th percentile. Who did the best on the test (in other words, who had the highest score)?

		Jill
		Lisa
		Ellianna
		The performance of all three was identical

A distribution of z-scores always has a mean of _____ and a standard deviation of _____.

		0, 1
		1, 0
		1, 1
		0, 0

Which of the following is the best interpretation of what the 65th percentile of a distribution means?

		65% of the scores fall equal to or above the 65th percentile
		65% of the scores fall equal to or below the 65th percentile
		65% of the scores are equal to, or fall at, the 65th percentile
		65% of the scores fall at the 65th percentile about 65% of the time

Which of the following sets of correlations correctly orders the highest to lowest degree of relationship between two variables (i.e., the highest degree of relationship between two variables to the lowest degree of relationship between two variables)?

		-0.96, +0.72, +0.10, -0.03
		-0.03, +0.10, +0.72, -0.96
		+0.72, -0.96, +0.10, -0.03
		+0.72, +0.10, -0.03, -0.96

Suppose a correlation between height (X) and weight (Y) for adults is +0.89. What percentage of the variability in the data is due to the relationship between height and weight?

		89%
		67%
		79%
		25%

We know that college GPA is positively correlated with salary after college. If we use knowledge of a student's GPA to predict his or her salary, the predictor variable is _______ and the criterion variable is _______.

		GPA; salary
		salary; GPA
		salary; the correlation between GPA and salary
		GPA; the correlation between GPA and salary

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

What is COVxy (the covariance)?

		-1.70
		+1.70
		-2.30
		+2.30
		-3.22
		+3.22

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

What is Sy (the standard deviation of Y)? In other words, the square root of the variance of the Y variable.

		0.31
		0.55
		4.44
		19.67
		0.497
		0.70

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

The Pearson Correlation Coefficient (r) is:

		r = -0.90
		r = +0.90
		r = +0.79
		r = -0.79
		r = -0.95
		r = +0.95

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

What is the slope (b)?

		-0.01
		-2.30
		4.44
		-0.14
		19.67
		3.22

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

What is the y-intercept (a) for this data?

		6.05
		6.67
		7.95
		8.33
		57.90
		5.49

The following data have to do with the relationship between maternal smoking (# of cigarettes smoked per day,

which is variable X) and infant birth weight (which is variable Y). (∑X, ∑X2, ∑Y, ∑Y2, and ∑XY have already been

calculated for you and are shown below in red font.)

Cigarettes Per Day (X) X2 Infant Birth Weight (Y) Y2 XY

2 4 7.5 56.25 15.0

6 36 7.2 51.84 43.2

10 100 6.9 47.61 69.0

12 144 6.2 38.44 74.4

14 196 5.8 33.64 81.2

∑X = 44 ∑X2 = 480 ∑Y = 33.6 ∑Y2 = 227.78 ∑XY = 282.8

What is the regression equation for this data?

		ŷ = 7.85X + (-0.12)
		ŷ = 8.33X + (-2.30)
		ŷ = 4.44X + 8.33
		ŷ = -0.12X + 7.85
		ŷ = -0.14X + 7.95
		ŷ = 5.49X + (-0.14)

A psychologist studied self-esteem scores and found the sample data set of 57 people to be normally distributed, with a mean of 105 and a standard deviation of 6. What is the median of this distribution?

		6
		57
		105
		The median cannot be determined from the limited information given

INSTRUCTIONS FOR THE following questions below

If the question requires computation, do the calculations and then give or select the correct values using the following rule:

Keep at least 4 decimal places at intermediate steps of a calculation, and round your final answer to 2 decimal places, unless otherwise noted.

For example:
16.6667 would become 16.67 after rounding

A survey of Ohio University students was conducted to determine if there was a particular Green that was desired by students to live on. A sample of students responses are reproduced below. Do students prefer a particular Green? Use critical value = 5.99.

Use the numbers below for this question only!

West Green South Green East Green

36 57 75

What is the calculated chi-squared value?

Use the numbers below for this question only!

West Green South Green East Green

26 66 115

What would the

expected value for the West Green be?

A local sports bar wanted to determine whether Ohio University students prefer a particular type of food in their establishment. A sample of students responses are reproduced below. Do students prefer a particular type of bar food? Use critical value = 6.58.

Use the numbers below for this question only!

Nachos Pizza Chicken Wings Cheese Sticks

31 40 37 47

What would the expected value for Cheese Sticks be?

Use the numbers below for this question only!

Nachos Pizza Chicken Wings Cheese Sticks

40 37 39 44

What is the calculated chi-squared value?

Using a critical value of 6.58, was there a significant preference for what students eat in a sports bar based on the obtained chi-square value in Question 5?

Yes

In a study of binge drinking among undergraduates at Ohio University, a researcher was interested in gender differences as related to binge drinking and to drinking-related arrests. She wanted to know two things: (a) Is there a significant relationship between gender and binge drinking (as defined by 5 or more drinks at one sitting), and (b) Is there a significant relationship between gender and drinking-related arrests? A random sample of males and females were asked about their experiences with binge drinking and with drinking-related arrests.

Use the numbers below for this question only!

Binge Drinking?

YES NO Male 215 270 Female 216 235

What would the

expected value for the "male-yes" cell be?

Use the numbers below for this question only!

Binge Drinking?

YES NO Male 256 224 Female 272 235

What would the

expected value for the "female-no" cell be?

Use the numbers below for this question only!

Binge Drinking?

YES NO Male 44 27 Female 24 49

What is the calculated chi-squared value?

Using a critical value of 3.84, and based on the obtained chi-square value in Question 9, is there a significant relationship between gender and binge drinking?

Yes

Use the numbers below for this question only!

Experience Alcohol-related Arrest?

YES NO

Male 219 278

Female 229 232

What would the expected value for the "male-no" cell be?

Use the numbers below for this question only!

Experience Alcohol-related Arrest?

YES NO Male 201 235 Female 263 261

What would the

expected value for the "female-yes" cell be?

Use the numbers below for this question only!

Experience Alcohol-related Arrest?

YES NO Male 45 23 Female 25 51

What is the calculated chi-squared value?

Using a critical value of 3.84, and based on the obtained chi-square value in Question 13, is there a significant relationship between gender and alcohol-related arrests?

Yes

Which of the following is not a true statement about bar graphs?

		The horizontal axis does not need to be labeled for a bar graph.
		Bar graphs show percentages or frequencies in various categories.
		Bar graphs represent categorical data.
		Pictograms are similar to bar graphs except they use pictures related to the topic.

Papa Johns conducted a survey of 100 nursing students taking statistics to determine what toppings they preferred on their pizza. Data handlers converted students' responses into a pie (no pun intended) chart to display the results clearly to upper management. Did the data handlers do a good job in constructing a quality statistical picture? Examine the statistical picture below and if you see a feature that is problematic (e.g., inaccurate or misleading), place your cursor over that feature and click. If you change your mind, click on the clear button on the bottom left and you can begin again. If you decide the statistical picture contains no problematic features, click just above the word "cheese." (Hint: Check out the components of a well-designed statistical picture that are listed on page 7 of the Module 6 course notes, such as appropriate Title, correct Source, etc.)

If you are having problems getting your choice to register and save, then you are probably not using the Firefox browser. Switching to the Firefox browser should remedy the problem. If the problem persists, let your moderator know what your choice is BEFORE THE ASSIGNMENT DEADLINE!

What does the z

Z Score Transform Z scores, or standard scores, indicate how many standard deviations an observation is above or below the mean. These scores are a useful way of putting data from different sources onto the same scale.

What is z

Z-scores reveal to statisticians and traders whether a score is typical for a specified data set or if it is atypical. Z-scores also make it possible for analysts to adapt scores from various data sets to make scores that can be compared to one another more accurately.

What are z

The value of the z-score tells you how many standard deviations you are away from the mean. If a z-score is equal to 0, it is on the mean. A positive z-score indicates the raw score is higher than the mean average. For example, if a z-score is equal to +1, it is 1 standard deviation above the mean.

Why are z

First, using z scores allows communication researchers to make comparisons across data derived from different normally distributed samples. In other words, z scores standardize raw data from two or more samples. Second, z scores enable researchers to calculate the probability of a score in a normal distribution.