Statistics Exam 1
The size of a population is symbolized as ______, whereas the size of a sample is symbolized as ______.
N; n
Which of the following is a type of graphical display used to summarize qualitative, discrete data?
both A and B
The advantage of squaring the deviation of each score from the mean and then summing is that ______.
it produces a minimal positive solution that is not zero, as long as all scores are not exactly the same value
State the four scales of measurement in order from least informative to most informative.
nominal, ordinal, interval, ratio
The normal distribution is symmetrical, which means that ______.
scores above the mean are distributed the same as scores below the mean Answers:
Which of the following distributions has the largest variability?
scores: 1, 3, 6, 9, and 12
Which of the following is an example of a distribution with NO variability?
scores: 5, 5, 5, 5, 5, and 5
A researcher computes the definitional formula for SS, as finds that E(x-M)2 = 44. If this is a sample of 12 scores, then what would the value of sample variance be using the definitional formula?
4.0
A researcher records the following assessment data: 42 ± 6 (M ± SD). The researcher only wants to sample participants scoring in the top 20% of this assessment. What is the cutoff score for the top 20% in this example?
47.04
A researcher computes the computational formula for SS, as finds that Ex= 22 and Ex2= 126. If this is a sample of four scores, then what would SS equal using the computational formula?
5
As a general rule, a simple frequency distribution should have between ______.
5 and 20 intervals
A researcher computes the definitional formula for SS, as finds that E(x-M)2 = 112. If this is a sample of 20 scores, then what would the value of population variance be using the definitional formula?
5.6
A researcher records the following scores: 5, 3, 7, 6, 2, 8, 0, and 1. In terms of these data, the sum of the squared differences of scores from their mean is ______.
60
A psychologist treats 16 patients and records the number of sessions required to complete a behavioral therapy treatment for each patient. She computes SS = 800. Assuming the 16 patients constitute all patients under her care (so the population of her patients), what is the standard deviation for these data?
7.1 sessions
A researcher records the time in seconds it takes a sample of participants to walk alone through a dark portion of campus. The researcher computes SS = 1,200. Assuming that a sample of 25 participants was observed in this study, what is the standard deviation for these data?
7.1s
What is the percentile point at the 80th percentile in the following distribution? **graph**
8
A researcher records the following body mass index (BMI) scores for a group of participants: 28.4 ± 1.6 (M ± SD). Participants who score between 25 and 30 on this scale are categorized as overweight. What percentage of participants fell in this overweight category?
8247
A professor records the following final exam scores: 78 ± 7 (M ± SD). Students scoring in the top 14% get an A. What is the cutoff score for the top 14% in this example?
85.56
A researcher measures the time (in seconds) it takes a sample of 26 participants to respond to a stimulus presented on a computer screen. The standard deviation for response times is 6. In this example, what is the value for SS?
900
Most behavior is believed to ______ a normal distribution.
approximate
The degrees of freedom for the sample variance ______.
are equal to the sample size minus one
Which of the following requires the calculation of a real range?
frequency distributions for grouped data
A researcher summarizes a set of frequency data into five intervals. This is an example of a frequency distribution for ______.
grouped data
Interval scales of measurement ______.
have equidistant scales
A graphical display for grouped frequency distributions with continuous data is called a ______.
histogram
A researcher records the time it takes to complete a memory task in a sample of 25 participants. He finds that the average participant completed the test in 43 s. The average time to complete this task is called a(n) ______.
sample statistic
Which of the following describes a descriptive statistic?
summarize
You are interested in measuring the construct, reinforcement. Which of the following measures for this construct is quantitative and continuous?
the size of a reward in grams
Which of the following is NOT a characteristic of the mean?
Delete a score above the mean and the mean will increase.
A researcher records the following data for how participants rated the likability (on a scale from 1 = not liked at all to 7 = very likable) of an individual who blushed after making a mistake: 5, 4, 7, 6, 6, 4, 6, 7, 2, 5, and 6. Is the mode equal to the median in this example?
Yes
A therapist has a goal to reduce the mean number of patient symptoms expressed for a particular disorder to two symptoms per day. Following therapy, she determines that the z score for two symptoms per day is 0. Assuming these data are normally distributed, did she reach her goal?
Yes, because a z score of 0 is the average, or mean.
A researcher selects a sample of six professors, six students, and six administrators at a local school and has them rate the effectiveness of an innovative new teaching style. In this example, is it possible that the weighted mean ratings will equal the arithmetic mean for the entire sample of 18 participants?
Yes, because there are an equal number of participants in each sample.
Given the same set of data for a population and sample, would the mean for both data sets be equal?
Yes, this would be true anytime both data sets are the same.
A researcher measures the time (in seconds) that it takes children to complete a basic reading skills task. What type of graphical display would be most appropriate for summarizing the frequency of children falling into different intervals of time?
histogram
A researcher measures the weight (in ounces) of newborn infants in the month of March. What type of graphical display would be most appropriate for summarizing the frequency of infants falling into different intervals of weight?
histogram
Each of the following is an example of quantitative data, except ______.
political affiliation
A psychologist reviews her notes for all her patients and determines that on average her patients complete therapy in 24 days. The average time to complete therapy among all her patients is called a(n) ______.
population parameter
A characteristic (usually numeric) that describes a population is called a ________.
population parameter.
The proportion or fraction of times an outcome is likely to occur is referred to as ______.
probability
Scores far from the mean are located in the ______ of a normal distribution.
tails
What is the implication for the tails of a normal distribution being asymptotic?
that extreme scores are possible in the tails of a normal distribution
Which of the following can be used to estimate the median?
the 50th percentile of a cumulative percentage distribution
A researcher records 17 scores. What is the median position of these scores?
the 9th score in numeric order
A researcher records 52 scores. What is the median position of these scores?
the average of the 26th and 27th scores in numeric order
Bar charts are a lot like histograms, except ______.
the bars displayed in the graph do not touch
A researcher records the following scores for attention during a video game task for two samples. Which sample has the largest standard deviation?Sample A: 10, 12, 14, 16, and 18Sample B: 20, 24, 28, 32, and 36
Sample B
_________ refer(S) to how the properties of numbers can change with different uses.
Scales of measurement
Which of the following statements about a weighted mean is true?
The weighted mean is used to compute the combined mean for two or more samples of scores in which the number of scores in each sample is disproportionate or unequal.
When cumulating frequencies from the top down, the data are discussed in terms of ______.
all of these
When df are in the denominator, the sample variance is ______.
all of these
Which of the following describes the definitional formula for variance?
all of these
Which of the following is a type of graphical display used to summarize quantitative, continuous data?
all of these
Which of the following is consistent with the empirical rule?
all of these
Which of the following is true about the computational formula for variance?
all of these
A population can be ______ group of interest to a researcher.
any
A researcher reports that the time (in minutes) it takes children who are "picky eaters" to finish their vegetables is negatively skewed, with children finishing their vegetables in 4.2 ± 1.0 (M ± SD) minutes. Based on Chebyshev's theorem, we can conclude that ______.
at least 89% of children finished their vegetables in 1.2-7.2 min
What terms refer to the meaning of each of the following measures, respectively: mean, median, and mode.
average, middle, and most
A researcher records the number of children at a local school from single-, divorced-, and married-parent homes. These frequency data would be best displayed as a ______.
bar chart
The mathematical term Ex is the numerator for ______.
both A and B
Which of the following is required to locate proportions of area under the normal curve?
both A and B
The following is a simple frequency distribution table. Suppose we convert this table to a cumulative frequency distribution. The frequencies in each interval of the cumulative frequency distribution would be **graph**
both A and B, depending on how the data were summarized
Grouped data are to ungrouped data as ______.continuous is to discrete
continuous is to discrete
Which of the following is not a step to locate a proportion in a normal distribution?
convert a proportion to a standard normal z score
Based on the following graphical summary display, what research design was used to record and analyze these data?
correctional
The distribution of annual household income in the United States is positively skewed. If the median annual income is about $56,000, this implies that the mean annual household income in the United States is ______.
larger
The ______ is the percentage of scores with values that fall below a specified score in a distribution.
percentile rank
_________ data describes numeric aspects of phenomena; whereas ________ data describes nonnumeric aspects of data.
quantitative; qualitative
Three key elements of control that allow researchers to draw cause-and-effect conclusions are ______.
randomization, manipulation, and comparison/control
The median would be used to describe which of the following variables?
rankings
A researcher compares the amount of college debt (in dollars) that undergraduate students incur up to their 4-year degree. College debt is on what scale of measurement?
ratio
To determine the interval width, we divide the ______ by the number of intervals.
real range
To construct a pie chart, first distribute the data as ______.
relative percentages
A distribution of z scores are distributed in what type of unit of measurement?
standard deviation units
The ______ converts any normal distribution with any mean and any variance to a standard normal distribution with a mean of 0 and variance of 1.
standard normal transformation
The total number of possible outcomes for a random variable is referred to as ______.
the sample space
A researcher identifies college students as a group of interest to test her hypothesis. She then identifies a few local college students and selects a small group of the local college students to be observed. In this example, the sample is ______.
the small group of college students who here observed
An interquartile range removes ______.
the top and bottom 25% of scores in a distribution before calculating range
The normal distribution has all of the following characteristics, except that ______.
the total area under the curve is greater than 1.0
A percentile point is ______.
the value of a score on a measurement scale below which a specified percentage of scores in a distribution fall
All other things being equal (so assuming that the value of SS never changes), as sample size increases, ______.
the value of sample variance decreases
The mode can be used with the mean to describe which of the following variables?
the winning percentage of teams in a league
The mean can take on any value and the standard deviation can take on any positive value. Therefore, ______.
there are an infinite number of possible normal distributions
A relative frequency distribution is appropriate when ______.
there are large frequency counts in each interval
Which of the following is not a step to locate a score in a normal distribution?
transform a raw score (x) into a z score
Regardless of the number of scores in a distribution, the range only includes ______ score(s) in its calculation.
two
Which of the following is not a symbol used with samples ______.
u
The population mean is symbolized as ______, whereas the sample mean is symbolized as ______.
u; M
A researcher determines that students are active about 60 ± 12 (M ± SD) minutes per day. Assuming these data are normally distributed, what is the z score for students being active 48 min per week?
-1.0
A researcher determines that students study an average of 80 ± 20 (M ± SD) minutes per week. Assuming these data are normally distributed, what is the z score for students studying 60 min per week?
-1.0
What is the z score for scores in the bottom 5%?
-1.645
A researcher records the following scores for an Olympic gymnast following her routine: 9.9, 9.8, 9.6, 9.5, 9.7, 9.1, 8.9, and 9.8. What is the range for the scores?
1.0 (9.9 to 8.9)
What is the percentile point at the 50th percentile for the following distribution?
25
A researcher selects a sample of 6 men and 11 women. She asks participants to rate the likelihood they would do female-stereotyped jobs (such as nursing or school teaching) on a scale from 1 = not likely at all to 5 = very likely. Men indicated that they would be less likely to do these jobs (M = 2.1) compared with women (M = 4.3). What is the weighted mean for the combined sample of 17 total participants?
3.5
What is the z score for scores in the top 2.5%?
+1.96
A researcher records the following number of birdcalls made during an experimental session with robins: 7.2 ± 0.6 (M ± SD). Assuming these data are normally distributed, what is the probability that robins made more than nine birdcalls during this experimental session?
.0013
A percentile is ______.
a percentile point
Ungrouped data can be distributed as ______.
categories
Qualitative data varies by ______; quantitative data varies by ______.
class; amount
A percentile is also called a ______.
percentile point
Which of the following is required to locate z scores with a given proportion?
both A and B
The following frequency distribution is an example of **graph**
ungrouped data
The sum of relative frequencies for each interval is ______.
1.00
escriptive statistics are procedures used to ______.
all of these
A simple frequency distribution ______.
all of these
Each deviation in the numerator for variance is squared because ______.
without squaring each deviation, the solution for SS would be zero
A reason for squaring deviations to compute SS in the numerator includes which of the following?
all of these
What is the z score for scores in the bottom 10%?
-1.28
Which of the following terms are least likely to be used to describe qualitative data?
. numeric
A researcher records the following times (in seconds) that it took a group of mice to complete a maze: 23 ± 4.1 (M ± SD). The top 10% of mice finishing with the fastest times will be placed in a "maze bright" group. What is the cutoff time to be placed in this group?
28.25 s
Fill in the missing values for A and B in this frequency distribution table: **graph**
A = 3.2, B = 13
A researcher records the sound (in decibels) during a series of lessons taught by a substitute teacher at a local elementary school. In his study, he found that the sound was 80 ± 6 (M ± SD) decibels. Assuming the data are normally distributed, which of the following is an appropriate conclusion?
At least 95% of classes were between 68 and 92 decibels.
______ is the variable that is believed to change in the presence of the independent variable.
Dependent variable
______ are measured in whole units or categories that are not distributed along a continuum.
Discrete data
A researcher measures the mean time (in seconds) it takes two groups of children to complete an activity task. She finds that Group A (M = 22 s) completed the task more quickly than Group B (M = 36 s). She then computes a weighted mean for both groups combined and calculates = 26. Based on the information provided, which group had a larger sample size?
Group A
Which of the following is a property of the standard deviation?
Multiplying each score by the same constant will change the standard deviation by that constant.
A researcher records a sample of 30 exam scores and finds that if these data were treated as a population, that the population variance calculation for these data is larger than the sample variance calculation for these same data. Is this outcome for variance possible?
No, the sample variance will be larger because SS is divided by degrees of freedom in the denominator of the variance formula.
A researcher records the following data for the number of complaints filed (per day) following a controversial policy change at a local business: 3, 8, 5, 0, 4, 6, 2, 1, 1, 4, 2, and 0. Is the mean equal to the median in this example?
No; the mean is larger than the median
A researcher records the following data for the number of times an interviewer is interrupted during a series of interviews: 0, 0, 3, 2, 5, 3, 0, 8, 0, 2, 1, and 1. Is the mode equal to the median in this example?
No; the median is larger than the mode.
A researcher records the following data for the time (in seconds) it takes five rats to cross an electrical grid to obtain reinforcement on the other side: 12, 9, 13, 4, and 12. Is the mean equal to the mode in this example?
No; the mode is larger than the mean.
To measure attraction, a researcher records the following data for the distance (in inches) between two persons sitting in a waiting room: 46, 32, 10, 23, 18, 46, and 60. Is the mode equal to the median in this example?
No; the mode is larger than the median.
A researcher distributes frequencies into the following intervals: 3-6, 7-10, 11-15, 16-18, 19-22, and 23-26. What is wrong with this frequency distribution?
The interval width is unequal.
Which of the following is NOT a rule for constructing a simple frequency distribution?
The number of intervals should equal the number of values measured.
Assuming N (doesn't equal) n and all data are otherwise the same, how will the value of the sample variance be different from the population variance?
The sample variance will always be a larger value than the population variance.
State whether the first area is bigger, the second area is bigger, or the two areas are equal: the area to the right of the mean, or the area between z = ±1.00.
The second area is bigger.
Which of the following is the best explanation for why the standard deviation is almost always reported with the mean?
The standard deviation measures the spread of scores from the mean, so it is important to know both the mean and the standard deviation.
A student scores in the 80th percentile on an exam. What does this mean in comparison to all other students?
The student scored higher than 80% of all others who took the exam.
Quantitative measures can be ____________.
both A and B
A researcher reports, "the average patron (n = 22) in a local bar consumed more than twice the number of drinks (per day) on weekends (M = 5.4 drinks) compared to weekdays (M = 2.3 drinks)." Although not stated directly, how do we know that the patrons in this study constitute a sample, and not a population of patrons at this local bar?
both B and C
Adding the same constant to each score in a distribution (or subtracting the same constant from it) will ______.
cause the mean to change by that constant
Multiplying or dividing each score in a distribution by the same constant will ______.
cause the mean to change by that constant
The procedure of converting a categorical variable to numeric values, is called _________.
coding
A researcher records the number of votes for each of five candidates running for class president. Based on her presentation of the following results, what type of statistics did she use? **graph**
descriptive statistics
The use of tables and graphs to summarize data is an example of___________.
descriptive statistics.
The sample variance is computed by dividing SS by ______; whereas the population variance is computed by dividing SS by ______.
df; N
Statistical analysis allows researchers to ______.
evaluate scientific observations
A researcher asks participants to estimate the calories they consume in a meal. The researcher records the following estimates: 450, 426, 310, 500, and 220. If the researcher removes the estimate of 220 (perhaps because the participant drops out of the study), then the value of the mean will ______.
increase
Procedures that allow researchers to infer or generalize observations made with samples to the larger population from which they were selected best describes ______.
inferential statistics
A researcher records the time (in seconds) that participants arrive late for a scheduled research study. Assuming these data are normally distributed, which measure of central tendency is most appropriate to describe these data?
mean
The ______ is the sum of all scores (in a sample or population) divided by the number of scores summed.
mean
A researcher asks adult participants to rank their top five favorite songs from their childhood. Based on the scale of measurement described, which measure of central tendency is most appropriate to describe these data?
median
The ______ is the middle value in a distribution of scores that are listed in numeric order.
median
The sum of the squared differences of scores from their mean is ______.
minimal
A researcher records the hospital admission rates for coronary heart disease at 10 local hospitals. She finds that two different hospitals had the highest overall rates of hospital admissions. Which measure of central tendency did this researcher use to describe these data?
mode
The variance and standard deviation can never be ______.
negative
Recording whom students study with describes ______ types of data; whereas recording the number of hours spent studying per week describes ______ types of data.
qualitative; quantitative
A researcher asks participants to estimate the height (in inches) of a statue that was in a waiting area. The researcher records the following estimates: 40, 46, 30, 50, and 34. If the researcher removes the estimate of 40 (say, due to an experimenter error), then the value of the mean will ______.
remain the same
Which of the following best describes an independent variable
the manipulated variable
The fact that the sum of the differences of scores from their mean is zero best illustrates that ______.
the mean is the "balance point" of a distribution
A measure of the average squared distance of scores from the mean is called the ______.
variance
The ______ is an arithmetic mean of a weighted or disproportionate set of scores.
weighted mean
The unit of measurement distributed along the x-axis of a standard normal distribution is referred to as a ______.
z score
What is the z score for scores in the top and bottom 2.5%?
±1.96
The range, a measure of variability, ______.
all of these
The sum of the squared deviations of scores from their mean ______.
all of these
A researcher records the following response times to a visual stimulus: 23 ± 3.1 (M ± SD) seconds. Assuming these data are normally distributed, what is the probability that participants responded in 20 s or less?
.1660
A researcher has participants choose between three advertisements. She finds that 54 prefer Ad A, 86 prefer Ad B, and 60 prefer Ad C. The probability or proportion of participants preferring Ad B is ______.
.43
A counselor records the number of disagreements (per session) among couples during group counseling sessions. If the number of disagreements is distributed normally as 4.4 ± 0.4 (M ± SD) disagreements, then what proportion of couples disagree at least 4 times during each counseling session?
.8413
Measures of variability can range in value from ______.
0 to + infinity
Which of the following is a possible value for the standard deviation of a normal distribution?
0.5
A therapist goes through her records and finds that 200 of her 400 patients showed significant improvement in mental health over the past year. Hence, the probability of her patients showing significant improvement in mental health is ______.
0.50
The standard normal distribution is normally distributed with a mean of ______ and a variance of ______.
0; 1
A professor finds that the students scored a 76 ± 8 (M ± SD) on the final exam. On this exam, a score of 90 is an A. Assuming these data are normally distributed, what is the z score for 90 (the cutoff for an A)?
1.75
A news poll showed that voters had no preference for either of three candidates. In this example, the probability of a vote for, say, Candidate A equals ______.
1/3
What is the percentile point at the 90th percentile in the following distribution? **graph**
10
A researcher decides to split scores on an exam into quartiles. She determines that a score of 64 is at the 25th percentile, a score of 74 is at the 50th percentile, and a score of 80 is at the 75th percentile. What is the interquartile range (IQR) for these data?
16
A researcher computes the computational formula for SS, as finds that Ex= 39 and Ex2 = 271. If this is a sample of six scores, then what would SS equal using the computational formula?
17.5
A researcher records the following times (in seconds) that it took a group of students to complete an exam: 18 ± 2 min (M ± SD). How long did it take 80% of students to complete the exam?
19.68 min
A researcher finds that 12% of participants make between three and five visits to a physician each year. What are the real limits for this interval?
2.5-5.5
A researcher finds that 12 persons in a sample of 60 reported getting between 4 and 6 hr of sleep per night. What is the relative percentage for this interval?
20%
The following is a simple frequency distribution table. If we convert this frequency distribution to relative percentages, which of the following gives the corresponding relative percentages in each interval listed from the top down?
20%, 13%, 17%, 33%, 17%
A researcher measures the number of tasks completed by participants during a 5-min multitasking session. If the number of tasks completed is distributed normally as 6.3 ± 1.0 (M ± SD) tasks, then what is the probability that participants completed less than 8 tasks?
9554
State the type of graphical display for Graph A and Graph B. **graph**
B is a bar chart; A is a histogram.
A researcher records the following motor assessment scores for two samples of athletes. Which sample has the largest standard deviation?Sample A: 8, 10, 12, 15, and 18Sample B: 16, 18, 20, 23, and 26
Both samples have the same standard deviation.
A researcher records the following scores on a working memory quiz for two samples. Which sample has the largest standard deviation?Sample A: 2, 3, 4, 5, 6, 7, and 8Sample B: 4, 5, 6, 7, 8, 9, and 10
Both samples have the same standard deviation.
When cumulating frequencies from the bottom up, the data are discussed in terms of ______.
all of these
___________ are measured along a continuum at any place beyond the decimal point.
Continuous data
Why is it important to divide by df to compute sample variance?
Doing so makes the sample variance an unbiased estimator of the population variance.
Each of the following are interval scale measurements, except_________.
Duration of sleep (in hours)
______ is the variable in an experiment that is manipulated between conditions being observed.
Independent variable
A researcher records the following data: 4, 4, 4, 4, and 3. How would you describe the variability of these data?
It is very small (close to 0) because scores are approximately the same
A researcher measures the amount of coffee consumed by college students while studying during the final exam week. In her study, she found that students drink 2.3 ± 0.8 (M ± SD) cups of coffee per study session. Assuming the data are normally distributed, which of the following is the most appropriate conclusion?
Most students drink between 1.5 and 3.1 cups of coffee per study session.
A researcher records the number of classroom interruptions during each of two class sessions. Which session has the largest standard deviation?Session A: 12, 15, 18, 24, and 30 Session B: 8, 10, 12, 16, and 20
Sample A
A parent decides to reward her child if he eats an average of at least five bites of his vegetables at dinner during the first week. She finds that her child ate 4 ± 0.8 (M ± SD) bites per meal for the first week. Assuming these data are normally distributed, should this parent reward her child?
No, because the z score for 5 bites is greater than 0.
Two normal distributions are observed. The first distribution has a mean of 12 and a standard deviation of 2. The second distribution has a mean of 0 and a standard deviation of 2. For which distribution will the z score for the mean be larger?
None, the z score will be the same.
A researcher distributes frequencies into the following intervals: 1-10, 11-20, 21-30, 31-40, 41-50, and 51 and above. What is wrong with this frequency distribution?
One interval is an open class.
Which of the following is NOT a characteristic of probability?
Probability is most useful for describing fixed events.
Researcher A measures academic preparedness as the percent correct responses on an entrance exam; Researcher B measures academic preparedness as the current class rank of students. Which researcher measured academic preparedness as discrete data?
Researcher B
A researcher measures the number of trials it takes two samples of participants to master a new task. In both samples, SS = 240. Sample A consisted of 12 participants and Sample B consisted of 18 participants. Which sample is associated with the largest variance?
Sample A
Which characteristic of a histogram implies that it summaries continuous data?
The vertical bars touch at the upper boundary of each interval.
A researcher records the number of individual instruments identified by students listening to a piece of classical music. He splits the data into quartiles and reports that students correctly identified three instruments at the 25th percentile, five instruments at the 50th percentile, and eight instruments at the 75th percentile. What are the IQR and SIQR for these data?
The IQR is 5; the SIQR is 2.5.
How is the sample variance computed differently from the population variance?
The calculation in the denominator is different.
State the problem with this simple frequency distribution. **graph**
The class intervals overlap.
State whether the first area is bigger, the second area is bigger, or the two areas are equal: the area to the left of z = 1.00, or the area to the left of z = -1.00.
The first area is bigger.
Which of the following describes the largest proportion in a z distribution?
The proportion of area between z = +1 and z = -1.
A researcher reports that "the average shopper in the sample (n = 12) purchased $65.00 worth of items ( = $65.00) during a busy shopping day." What mistake was made is this citation?
The sample mean is written using the wrong notation.
A professor grades 120 research papers and reports that the average score was an 80%. What do we know about the sum of the differences of these 120 scores from their mean of 80%?
The sum of the differences is equal to zero.
State whether the first area is bigger, the second area is bigger, or the two areas are equal: the area to the left of z = 0.80, or the area to the right of z = -0.80.
The two areas are the same.
Researchers rarely have access to entire populations. How do researchers resolve this limitation?
They record data from a sample of people in the larger population in order to make inferences concerning characteristics in that larger population.
When would it be appropriate to calculate a population mean?
When data are measured for all members of a population.
A researcher records the following data for the number of different food items chosen by seven participants in a buffet-style setting: 1, 6, 2, 5, 4, 3, and 7. Is the mean equal to the median in this example?
Yes.
A researcher records the following data for the number of dreams recalled during a night of sleep for 10 college students: 3, 2, 4, 4, 3, 1, 1, 0, 2, and 0. Is the mean equal to the median in this example?
Yes.
A researcher wants to determine how many participants will take less than 24 s to complete a cognitive performance task. If he constructs a frequency distribution for these data, what type of distribution would be most appropriate to answer his question?
a cumulative frequency distribution from the bottom up
A psychologist wants to know how many of her clients continue with therapy for at least 12 days. If she constructs a frequency distribution for these data, what type of distribution would be most appropriate to answer her question?
a cumulative frequency distribution from the top down
A health practitioner measures the heart rate (in numbers of beats per minute) of patients under low, moderate, and high stress levels. Heart rate can be best described as _________.
a discrete data
The SIQR can be defined as ______.
a measure of half the distance between Q3 and Q1
Suppose that a researcher is interested in a group of 10 million people who paid to see a movie playing in theaters. In this example, the 10 million moviegoers would be regarded as ______.
a population of moviegoers who paid to see the movie in a theater
A researcher records the following time spent sleeping per night (in hours) in a group of participants: 5.8 ± 1.8 (M ± SD). The researcher decides to categorize participants who sleep between 6 and 8 hr as moderate sleepers. What percentage of participants fell in this category?
about 35%
Which of the following will decrease the value of the mean?
adding a score below the mean
A researcher distributes frequencies into the following classes: absent, tardy, and present. What type of data is distributed?
all of these
A staff member records the number of victories (per 10-game season) for a new football coach during his first three seasons with a team. The coach won 1, 3, and 8 games, respectively, over the three seasons. Which conclusion is appropriate?
all of these
A theoretical distribution that evenly distributes data around the mean, median, and mode is called the ______.
all of these
By definition, the probability of an outcome or event is ______.
all of these
Grouped data can be distributed ______.
all of these
In a normal distribution, 50% of all data ______.
all of these
The mean is an appropriate measure of central tendency for ______.
all of these
The median is an appropriate measure of central tendency for ______.
all of these
The mode is an appropriate measure of central tendency for ______.
all of these
A researcher selects a sample of 24 participants and has them complete a survey on dating preferences. In this example, what are the degrees of freedom for sample variance and what does this represent?
df = 23; it represents the number of scores that are free to vary in a sample.
Recording the number of dreams recalled is an example of ______ data; whereas recording the time (in minutes) spent in a dream stage of sleep is an example of ______ data.
discrete; continuous
The mean would be used to describe which of the following variables?
distance traveled in miles
A researcher visits a population of 1,200 local residents to determine the proportion of local residents who support a new smoking ban. In this case, the sample space is ______.
equal to the population of 1,200 local residents
The definitional formula ______ the computational formula for SS.
equals
A researcher finds that the average preschool-aged child drinks two cups of milk per day. Assuming these data are normally distributed, the z score for the average cups per day in this example is ______.
exactly equal to 0
A researcher tests whether the dosage level of some drug (low, high) causes significant differences in health. To do this, the researcher randomly assigns rat subjects to relieve a low or high dosage of the drug and records health-related measures in both groups. the type of method described is ___________.
experimental
Which of the following research designs is used to determine the causes of behavior that help to explain why the behavior occurs?
experimental
Three research methods common to research in the behavioral sciences are _________.
experimental, quasi-experimental, and correlational
The three steps for constructing a simple frequency distribution are ______.
find the real range, find the interval width, and construct the frequency distribution
A therapist observes that spouses are more likely to forgive their partners for lying to them if they find out the truth from their spouse and not a third party. In this example, the dependent variable is ______.
forgiveness
A ______ is plotted at the midpoint of each interval, whereas a ______ is plotted at the upper boundary of each interval.
frequency polygon; ogive
The range of scores between the upper and lower quartiles of a distribution is called the ______.
interquartile range
A researcher measures the body temperature (in degrees Fahrenheit) of participants immediately before and immediately following sleep. Temperature is what scale of measurement?
interval
The range of scores in each interval of a grouped frequency distribution is called the ______.
interval width
Grouped data are distributed into ______, whereas ungrouped data are distributed into ______.
intervals; categories
The ______ is the value that occurs most often or at the highest frequency in a distribution.
mode
An animal researcher measures the number of times a rat presses a lever located at the right, center, and left of a cage for a food reward. What scale of measurement is the location of lever pressing?
nominal
An education counselor records the number of high school graduates enrolled in community colleges, 4-year colleges, and universities. What scale of measurement is the type of college?
nominal
The following distribution most closely approximates a ______.
normal distribution
Which graphical display lists percentages and not original scores?
ogive
A consultant ranks the five most needed areas of improvement for a local business. What scale of measurement are the rankings?
ordinal
A movie critic rates a movie on a scale from 1 (lowest) to 4 (highest) stars. What scale of measurement are the ratings?
ordinal
A cumulative percentage summary that indicates the percentage of scores at or below a given value is called a ______.
percentile rank
If a portion of people from a population are asked to complete an assessment, then the average score among that group of people would be considered a ______.
sample mean
Which of the following values is NOT needed to compute sample variance using the computational formula, but is needed to compute the definitional formula?
sample mean
Which type of mean is used to describe a portion of individuals in a given population?
sample mean
A characteristic (usually numeric) that describes a sample is called a__________.
sample statistic
Researchers measure data in a ______ to learn more about individuals in the larger ______ of interest.
sample; population
Which of the following best describes a dependent variable?
the measured behavior
You are interested in measuring the construct, work expertise. Which of the following measures for this construct is quantitative and discrete?
the number of employees that work under an employee
What is the corresponding percentile of a percentile point?
the percentile rank
Which of the following measures of attraction is an example of a ratio scale measurement?
the physical proximity (in feet and inches) between two romantic partners