PSY 010 Exam 01

The use of tables and graphs to summarize data is an example of ______.

descriptive statistics

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

nominal

(adj.) existing in name only, not real; too small to be considered or taken seriously

As a general rule, a simple frequency distribution should have between ______.

5 and 15 intervals

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?

7.1 s

histogram

A graph of vertical bars representing the frequency distribution of a set of data. (continuous variables)

Standard Deviation (SD)

A measure of the variability of a data set, calculated as the square root of the variance (V).

pie chart

A pie chart is a graphical display in the shape of a circle that is used to summarize the relative percent of discrete and categorical data in sectors.

ratio

A scale of measurement that has equal intervals between adjacent units. It also has a true zero point, indicating the absence of the quantity being measured.

cumulative frequency distribution

A tabular summary of quantitative data showing the number of data values that are less than or equal to the upper class limit of each class.

A researcher records the following scores on a working memory quiz for two samples. Sample A: 2, 3, 4, 5, 6, 7, and 8 Sample B: 4, 5, 6, 7, 8, 9, and 10 Which sample has a larger standard deviation?

A. Sample A B. Sample B C. Both samples have the same standard deviation. Ans: C

The median is an appropriate measure of central tendency for ______.

A. data that are positively skewed B. data that are negatively skewed C. data that are on an ordinal scale D. all of these Ans.D

The mean is an appropriate measure of central tendency for ______.

A.data that are unimodal and symmetrically distributed B. data that are on an interval or ratio scale C. data in which the mean, median, and mode are equal

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

Continuous data

continuous data

Data that can take on any value. There is no space between data values for a given domain. Graphs are represented by solid lines.

discrete data

Data with space between possible data values. Graphs are represented by dots.

______ are measured in whole units or categories that are not distributed along a continuum.

Discrete data

interval scale

Examples: • Fahrenheit or Celsius scale is a reasonable example: the difference in temperature between 26 -27 degrees and 70 -71 degrees is equal ( equal intervals ), and 70 is more than 26 ( order ), but there is no true zero point . The zero degree does not represent the complete absence of temperature (the absence of any molecular kinetic energy), it is just a reference point that is labeled as "zero".

ordinal scale

Examples: • Finishing order in a competition (first place = 1, second place = 2, ...) • Education level (less than high school = 1, high school = 2, some college = 3, ....) • US. News & World report rankings for top Psychology graduate school programs in the US, 2017 ( Stanford = 1, UC Berkeley = 2, Harvard = 3, ...)

ratio scale

Examples: • Many physical attributes are examples of ratio scale (reaction time, age). • The reaction time could be o second (true zero), and 20 seconds is longer than 10 seconds (order). • Similarly, a person could be 0 -year -old, and a person who is 30 years old is older than another who is 15 years old.

Nominal scale of measurement

Examples: • person's sex (male = 1, female = 2) • hair color (black = 1, brown = 2, blonde = 3, red = 4) • season of birth (spring = 1, summer = 2, fall = 3, winter = 4)

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.

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 a larger variance?

Sample A

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

Mean

The average of a set of numbers

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.

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 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.

Which characteristic of a histogram implies that it summaries continuous data?

The vertical bars touch at the upper boundary of each interval.

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 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.

bar chart

a chart with bars whose lengths are proportional to quantities (discrete & categorical variables)

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

interval

a data type which is measured along a scale, in which each point is placed at equal distance from one another. Interval data always appears in the form of numbers or numerical values where the distance between the two points is standardized and equal.

Parameter

a numerical descriptive value summarizing population data

Statistic

a numerical descriptive value summarizing sample data

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

average, middle, and most

Ordinal

being of a specified position or order in a numbered series

Which of the following is a type of graphical display used to summarize qualitative, discrete data?

both bar chart and pie chart

The mathematical term ∑ X is the numerator for______.

both population mean and sample mean

Deviation

distance of one score from the mean

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

interval

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

mean

The variance and standard deviation can never be ______.

negative

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

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

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

ordinal

Each of the following is an example of quantitative data, except ______.

political affiliation

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

quantitative; qualitative

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

Qualitative

relating to, measuring, or measured by the quality of something rather than its quantity.

Quantitative

relating to, measuring, or measured by the quantity of something rather than its quality.

Researchers measure data in a ______ to learn more about individuals in the larger ______ of interest.

sample; population

relative percent distribution

summary display that distributes the percentage of scores occurring in each interval relative to all scores distributed

Variance

the average of squared deviation scores from the mean.

A researcher records 52 scores. What is the median position of these scores?

the average of the 26th and 27th scores in numeric order

Range

the difference between the highest and lowest scores in a distribution

Median

the middle score in a distribution; half the scores are above it and half are below it

Mode

the most frequently occurring score(s) in a distribution

Sum of Squares

the sum of the squared deviation scores

The mode can be used with the mean to describe which of the following variables?

the winning percentage of teams in a league

Regardless of the number of scores in a distribution, the range only includes ______ score(s) in its calculation.

two

Each deviation in the numerator for variance is squared because ______.

without squaring each deviation, the solution for SS would be zero

scales of measurement

• Nominal: identity or classification, but no order • Ordinal: order , but unequal units • Interval: order + equal intervals , but no true zero • Ratio: order + equal intervals + true zero