stats hw 1

frequency polygon; ogive

A ________ is plotted at the midpoint of each interval, whereas a ________ is plotted at the upper boundary of each interval.

ordinal

A consultant ranks the five most needed areas of improvement for a local business. What scale of measurement are the rankings?

The sum of the differences is equal to zero.

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%?

there are large frequency counts in each interval

A relative frequency distribution is appropriate when

are equal to the sample size minus one

A researcher computes the definitional formula for SS, as finds that ∑(x-M)2 = 44. If this is a sample of 12 scores, then what would the value of sample variance be using the computational formula?

-nominal data -qualitative data -ungrouped data

A researcher distributes frequencies into the following classes: absent, tardy, present. What type of data are distributed?

Most students drink between 1.5 and 3.1 cups of coffee per study session.

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?

interval

A researcher measures the body temperature (in degrees Fahrenheit) of participants immediately before and immediately following sleep. Temperature is on what scale of measurement?

group A

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 seconds) completed the task more quickly than Group B (M = 36 seconds). 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?

Sample A

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?

yes

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?

95% of classes were between 68 and 92 decibels.

A researcher records the sound (in decibels) during a series of lessons taught by asubstitute teacher at a local elementary school. In his study, he found that the sound was80±6 (M±SD) decibels. Assuming the data are normally distributed, which of the following is an appropriate conclusion?

7.1 seconds

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?

the notation for both a sample mean and a sample size was used

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?

df = 23; it represents the number of scores that are free to vary in a sample.

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 figure represent?

3.5

A researcher selects a sample of 6 males and 11 females. 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 this entire sample of 17 participants?

experimental

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 receive a low or high dosage of the drug and records health-related measures in both groups. The type of method described is

nominal

An education counselor records the number of high school graduates enrolled in community colleges, four-year colleges, and universities. What scale of measurement is the type of college?

-summarize a set of scores or observations -organize a set of scores or observations -make sense of a set of scores or observations

Descriptive statistics are procedures used to

-the median -quartiles -percentiles

Fractiles are ways that data can be divided into two or more equal parts. An example of a fractile includes

sample mean

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

have equidistant scales

Interval scales of measurement

Researcher B

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?

nominal, ordinal, interval, ratio

State the four scales of measurement in order from least informative to most informative.

mean

The ________ is the sum of all scores (in a sample or population) divided by the number of scores summed.

are equal to the sample size minus one

The degrees of freedom for the sample variance

larger

The distribution of personal income for U.S. citizens is positively skewed. If the medianannual income is $44,000, this implies that the mean annual income is

-data that are normally distributed -data that are on an interval or ratio scale -data in which the mean, median, and mode are equal

The mean is an appropriate measure of central tendency for

interval width

The range of scores in each interval of a grouped frequency distribution is called

-is the difference between the largest (L) and smallest (S) value in a list of scores B) -is the most informative when used to describe data sets without outliers -includes only two values in its computation, regardless of the number of scores in a distribution

The range, a measure of variability,

find the real range, find the interval width, and construct the frequency distribution

The three steps for constructing a simple frequency distribution are

randomization, manipulation, and comparison/control

Three key elements of control that allow researchers to draw cause-and-effect conclusions are

real range

To determine the interval width, we divide the ________ by the number of intervals.

categories

Ungrouped data can be distributed as

average, middle, and most

What terms refer to each of the following measures, respectively: mean, median, and mode.

-greater than -at or above -at least

When cumulating frequencies from the bottom up, the data are discussed in terms of

sample mean

Which type of mean is used to describe a portion of individuals in a given population?

doing so makes the sample variance an unbiased estimator of the population variance

Why is it important to divide by df to compute sample variance?

continuous data

________ are measured along a continuum at any place beyond the decimal point.

quantitative; qualitative

________ data describe numeric aspects of phenomena; whereas ________ data describe nonnumeric aspects of data.