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Statistics ____ data in order to answer questions.

The characteristics measured by a researcher are called ____.

The objects being studied by a researcher are called ____.

In a correlational design, the two variables are simply measured; they are not ____ by the experimenter.

If two variables, X and Y, are found to be related in a correlational design, the three possible explanations for the relationship are:

(a) ____,

(b) ____,

(c) ____.

A third variable that could be the real cause of an apparent relationship between X and Y in correlational research is called ____.

____ is the hallmark of an experimental design.

In an experimental design, the ____ variable is manipulated or controlled by the experimenter.

The variable where the effect is measured in an experimental design is called the ____.

Experimental designs allow one to draw a conclusion about ____.

In a quasi-experimental design, cases are classified into ____ based on characteristics they already possess.

Though a quasi-experimental design looks like an ____ design, it is really a ____ design.

The mnemonic iced stands for ____.

A ratio-level number contains ____ information than a nominal-level number.

The mnemonic to help remember, in order, the four levels of measurement is ____.

Nominal-level numbers contain information about ____.

____-level numbers contain information about same/different and direction.

Because interval-level numbers have ____, we can meaningfully speak of distance between two scores.

Interval-level numbers have an ____ zero point and ratio-level numbers have a ____ zero point.

Proportions can be found for ____-level numbers.

A ____ is the larger group of cases that a researcher is interested in studying.

A number characterizing a sample is called a ____; a number characterizing a population is called a ____.

We use ____ letters as abbreviations for sample values and ____ letters as abbreviations for population values.

If a summary statement is used to describe a group of cases, it is a ____ statistic; if it is used to draw a conclusion about the larger population, it is an ____ statistic.

The letter we use as an abbreviation for a dependent variable is ____. The abbreviation for the number of cases in a group is ____. The symbol for adding up a group of scores is ____, the uppercase Greek letter sigma.

According to the American Psychological Association, final results should be rounded to ____ decimal places.

If one does round as one goes, carry at least ____ decimal places.

The local police department has come to a criminologist to help them evaluate a new type of disposable, plastic handcuffs. They are just as effective as metal handcuffs in terms of immobilizing someone who has been arrested and they are cheaper than metal handcuffs, but the police are concerned that the plastic ones might cause more abrasion to the skin of the wrist. The criminologist finds 20 volunteers, randomly divides them into two groups, cuffs one group with metal and the other with plastic, and then rides them around in a squad car for 20 minutes. After this, the criminologist measures the degree of abrasion on their wrists as the percentage of skin that is roughed up.

a. Generate a sentence that states the question the researcher is trying to answer.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

Some football players put streaks of black paint under their eyes because they believe that it helps them see better in sunny conditions and react more quickly. A sensory psychologist wants to see if this is really true. He gathers a group of volunteers and randomly divides them in two. Half get black paint applied under their eyes and half get flesh-color. The players are not allowed to look in the mirror, so they don’t know which color they have. The psychologist then gives them a reaction time task to measure, in milliseconds, how quickly they can respond to a change in a stimulus while bright lights are being shined at them.

a. Generate a sentence that states the question the researcher is trying to answer.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

Ever notice that some college students buy all the books for class, complete all the readings, do all the homework, and so on? These students usually end up with better grades as well. An education professor decided to investigate if these more conscientious students received better grades because they worked harder or because they were innately smarter. The professor got (a) a group of conscientious students from a number of different colleges and (b) a group of non-conscientious students from the same colleges, and compared the two groups in terms of a standardized IQ test.

a. Generate a sentence that states the question the researcher is trying to answer.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

A personality psychologist has kindergarten teachers use an empathy scale that ranges from 0 (not at all empathetic) to 100 (extremely high levels of empathy) to rate their students. Thirteen years later, when the students are ready to graduate from high school, he tracks them down and rates their level of mental health on a scale from 0 (very, very poor) to 100 (very, very good).

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

An economist believed that as nations become wealthier, they produce more greenhouse gases. He took a country and found both its gross domestic product (GDP) and the total tons of CO_{2} emissions for each year over the past 50 years.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

A consumer behavior researcher is curious as to whether, in terms of the monetary value of Christmas presents received, it makes a difference if a child is naughty or nice. She has parents classify their children as naughty or nice, then calculates how much the parents spent on Christmas presents for the two different groups of children.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

A political scientist is curious as to what influences voting behavior on taxes for school districts. She obtains a sample of voters and divides them, randomly, into three groups. One group serves as the control group, nothing is done to them. To one experimental group, she gives information about the school taxes that focuses on the positive—how the levy will improve student performance, make the community more attractive to young families, and so on. To the other experimental group, she gives negative information about the school taxes how much overall taxes will increase, how school taxes will take away funding from other projects, how wasteful the school district has been, and so on. She then measures, for each group, the percentage voting in favor of the school taxes.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

A neuroscientist believes that proteins form plaques in the brain that cause Alzheimer’s disease. He gets a sample of older adults, measures the nanograms/liter of protein in spinal fluid, and measures short-term memory as the percentage of words in a list that are recalled.

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, come up with a plausible confounding variable and explain how it affects both variables.

A meteorologist classifies cities in the United States in terms of winter weather: “dreary” (0) or “not dreary” (1). Type of winter weather (0 vs. 1) is measured at what level of measurement?

A social worker obtains the suicide rates for students at colleges in the United States. If the college has a suicide rate that is below average, he classifies it as −1. If the suicide rate is average, the college gets a 0, and if the suicide rate is above average, it gets a +1. The suicide rate (−1, 0, +1) is being measured at what level of measurement?

The owner of an automobile shipping company classifies cars in terms of size. If a car is a subcompact, she assigns it the value of 1. A compact car gets a 2, a mid size car a 3, and a full-size car a 4. At what level is she measuring car size?

The admissions committee at a college does not distinguish between different types of high school extracurricular activities. As far as it is concerned, being a member of the tiddlywinks club is equivalent to being student council president. On the admission form to the college, applicants are asked to report the number of extracurricular activities they were involved with in high school. The college is measuring extracurricular activities at what level?

The same college asks students to submit their SAT scores, but only on the math subtest. Subtest scores on the SAT range from a low of 200 to a high of 800, with 500 representing an average score. The SAT measures math skills at what level?

A nurse researcher measures how many minutes patients must wait before being seen by the triage nurse after they enter an emergency room. Wait time is measured at what level?

A housing developer advertises her houses as being fully carpeted (2), partially carpeted (1), or not carpeted (0). Amount of carpeting is measured at what level?

A person’s knowledge of English grammar is measured by a 50-item multiple choice test. Each correct answer is worth 2 points, so scores can range from 0 to 100. English grammar knowledge is being measured at what level?

If a person reads books for pleasure, he or she is classified as a “1”; if a person doesn’t read books for pleasure, he or she is classified as “0.” Whether or not a person reads books for pleasure is being measured at what level?

A person’s depression level is measured on a 20-item inventory where each item is a true/false item and is meant to measure depression. Each item endorsed in the “depressed” direction adds 1 point to the person’s score, so scores can range from 0 to 20. Depression level is being measured at what level?

A college dean wanted to find out which students were smarter: those seeking liberal arts degrees (like English or psychology) or those seeking professional degrees (like nursing, business, or engineering). From all the colleges in the United States, she picked 1,200 liberal arts majors and 1,000 professional degree majors. Each student took an IQ test and she calculated the average IQ for each group.

a. Is the group of 1,200 liberal arts majors a sample or a population?

b. If the college dean uses the averages in statements like, “The average intelligence of liberal arts students in the United States is 115.67,” is she treating the averages as statistics or as parameters?

c. If she uses the two averages to answer her question, is this an example of inferential statistics or descriptive statistics?

A political pollster calls 2,000 registered American voters and finds out whether they plan to vote for the Democratic or Republican candidate in an upcoming election. From this she predicts the outcome of the election. Is she using the information about the sample as a descriptive or as an inferential statistic?

Every 10 years, the United States Census Bureau attempts to collect information from all Americans. Assuming that they are successful, would it be a statistic or a parameter if the Census Bureau reported that 12.2% of Americans identify themselves as of African descent?

A college president wants to know what the average quantitative SAT is for the first-year class at her college. She calls the registrar and the registrar accesses the database for the entire first-year class to calculate the average. Does the average the registrar calculated correspond to a sample or a population?

Use this data set: 8, 9, 5, 4, 7, and 8. Find the following:

N

Use this data set: 8, 9, 5, 4, 7, and 8. Find the following:

ΣX

Use this data set: 8, 9, 5, 4, 7, and 8. Find the following:

ΣX^{2} =

Use this data set: 8, 9, 5, 4, 7, and 8. Find the following:

ΣX − 1

Use this data set: 13, 18, and 11 to find the following:

ΣX

Use this data set: 13, 18, and 11 to find the following:

ΣX^{2}

Use this data set: 13, 18, and 11 to find the following:

ΣX/N =

Use this data set: 13, 18, and 11 to find the following:

Σ(X − 14) =

Use the rounding rules to round the following.

12.6845 =

Use the rounding rules to round the following.

189.9895 =

Use the rounding rules to round the following.

121.0056 =

Use the rounding rules to round the following.

674.064005 =

Use the rounding rules to round the following.

22.467 =

Use the rounding rules to round the following.

37.97700001 =

Use the rounding rules to round the following.

2.53200005 =

Use the rounding rules to round the following.

99.995 =

A researcher gives different amount of X to different subjects and then measures how much Y each subject produces. She finds that subjects who got more X produce more Y and subjects who got less X produce less Y. She also finds no other variable that can account for the different amounts of Y that the subjects produce. What conclusion should she draw?

a. There is a relationship between X and Y.

b. There is a relationship between Y and X.

c. X causes Y.

d. Y causes X.

e. A confounding variable, Z, causes both X and Y.

f. There is not enough information to draw any conclusion.

Independent variable is to dependent variable as:

a. Controlled is to manipulated.

b. Relationship is to cause and effect.

c. Statistic is to parameter.

d. Parameter is to statistic.

e. None of the above

A sociologist believes that physical distress in cities leads to social distress. She measures physical distress by seeing how much graffiti there is. Based on this, she classifies cities as being high, moderate, or low in terms of physical distress. She randomly samples cities in North America until she has 10 cities in each category. She then measures social distress by obtaining the teenage pregnancy rate for each of these cities.

a. What question is the researcher trying to answer?

b. List the variables and label them as independent and dependent.

c. Determine what type of study is being done: correlational, experimental, or quasi-experimental.

d. If the study is correlational or quasi-experimental, name a plausible confounding variable and explain how it affects both variables.

A clinical psychologist administers a list of fears to measure how phobic people are. It has 10 items on it (such as spiders, snakes, height, darkness). For each item, a person answers “yes” or “no” as to whether he or she is afraid of it. Each yes equals 1 point, so scores can range from 0 to 10. The score on the fear survey is measured at what level of measurement?

A frequency distribution is a ____ of how often the values of a variable occur in a data set.

There are two types of frequency distribution tables: ____ and ____.

A basic frequency distribution just contains information about what ____ occur in a data set and what their ____ are.

____ tells how many cases in a data set have a given value or a lower one.

The abbreviation for cumulative frequency is____.

The cumulative frequency for the top row in a frequency distribution is equal to ____.

If one has ____ -level data in a frequency distribution, it should be organized in some logical fashion.

The ____ column in a frequency distribution is a restatement of the information in the cumulative frequency column.

When dealing with a variable that has a large range, a ____ frequency distribution usually makes more sense than an ungrouped frequency distribution.

As a general rule of thumb, grouped frequency distributions have from ____ to ____ intervals.

Having a small number of intervals may show the big picture, but the danger exists of losing sight of the ____ in the data set.

All intervals in a grouped frequency distribution should be the same ____ so the frequencies in different intervals can be compared meaningfully.

A ____ is the middle point of an interval.

If the value for a case in an interval is unknown, assign it the value associated with the ____.

Discrete numbers answer the question ____.

Discrete numbers take on ____ number values only.

____- and ____-level numbers are discrete numbers.

____ numbers answer the question “How much?”

If one has interval or ratio data, the first choice for a measure of central tendency to calculate should be a ____.

The median separates the top ____% of scores from the bottom ____% of scores.

The median is ____ influenced by outliers than is the mean.

A mean may be influenced by ____, which are extreme scores.

The sum of deviation scores equals ____.

The formula for a ____ is X − M.

Two sets of scores may be alike in central tendency, but can still differ in ____.

The three measures of central tendency covered in this chapter are ____, ____, and ____.

The two dimensions used in this chapter to summarize a set of data are measures of ____ and ____.

The distribution of prices of all the new cars sold in a year, including Ferraris, Lamborghinis, and other high-end cars, is probably:

a. Normally distributed.

b. Positively skewed.

c. Negatively skewed.

d. Not skewed.

If a researcher has a grouped frequency distribution for a continuous variable and there are five people in the interval ranging from 50 to 54, what X values should he assign them if he wants to assign values?

a. He should randomly select values from 50 to 54.

b. He should randomly select values from 49.5 to 54.5.

c. As there are five people and there are five integers from 50 through 54, he should assign them values of 50, 51, 52, 53, and 54.

d. 50.

e. 52.

f. 52.5.

g. 54.

For a row in the middle of a frequency distribution, either ungrouped or grouped, which statement is probably true?

a. f > f_{c}

b. f_{c} > f

c. f = f_{c}

d. None of these statements is ever true.

A researcher from a search engine company runs Internet searches and times how long each one takes. She found that 17 searches took 0.01 to 0.05 seconds; 57 took 0.06 to 0.10 seconds; 134 took 0.11 to 0.15 seconds; 146 took 0.16 to 0.20 seconds; 398 took 0.21 to 0.25 seconds; 82 took 0.26 to 0.30 seconds; and 56 took 0.31 to 0.35 seconds. Graph the frequency distribution and comment on its shape.

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