Exam 1 Statistics

Identify a RESEARCH hypothesis of the following example. ex. A sociologist is studying the difference between the men and women and average life expectancy.

A and C A.)Men have a greater average life expectancy than women C.)Men have a decreased average life expectancy compared to women.

According to the text, Pie charts are NOT effective for displaying the relative frequencies of a______ number of categories. They ARE recommended, however, when you have a _______ number of categories.

Large, small

Relative Frequency

frequency/sum of all frequencies (frequency/n)

The standard deviation is a number that explains:

how far, on average, the scores are from the mean

A sample distribution has an n of 10 scores, has a mean of 45 and a variance of 25. What is the standard deviation?

5

A frequency histogram bars are plotted using

A frequency histogram bars are plotted using real limits.

population

A population is all members of a specified group. Populations can be large, small or unknown.

A sociologist studying the prevalence of alcohol use among seniors in a particular high school asked 45 of these youth how many drinks they had consumed in the last week. Convert the following frequency distribution of responses (number of drinks) into a grouped frequency distribution containing four class intervals. What is the frequency of each class interval?

Apparent Limits: 0- 2, 3-5, 6-8 Frequency: 10, 21, 14

Identify the scale of measurement for the following military hierarchy: Lieutenant, Captain, Major

Ordinal

If the mean is 25 and the n = 100, which of the following is true?

The sum of x = 2500

A cumulative percent is also known as a percentile. (it is the percentage of scores that fall below the exact upper limit of the interval).

True

A sample is a relatively small representative group selected from a population.

True

Bar charts are particularly useful for showing change over time.

True

Both the variance and standard deviations are essentially averages

True

For ranked frequency distributions raw data is ordered by listing so that the highest number is at the top and the lowest number is at the bottom.

True

In a frequency polygon, the line connecting the midpoints, showing the pattern of the distribution of data, must be connected to the zero frequency, down at the abscissa on both ends of the distribution:

True

Scores that represent the center of a distribution are called measures of central tendency.

True

Stem and leaf displays are good for comparing two groups.

True

The difference between cumulative and relative frequencies is the following: A cumulative frequency (CF) is the total number of scores that fall below the upper limit of an interval, WHILE a relative frequency (rel f) is the proportion of scores from the distribution that fall within real limits of an interval.

True

The range is not a reliable measure of variability.

True

This is an example of a research hypothesis (Hr): Kids who watch violent media will act more aggressively on the playground than kids who do not watch violent media.

True

This is the formula to solve for a cumulative relative frequency: CF/N

True

When a distribution has zero skew, the mean, the median and the mode are the same.

True

μ is the symbol for the mean of a population.

True

Choose the true statement that completes the following sentence: The x-axis is ________________________

is where the independent variable is plotted

variable

any event or characteristic that can assume more than one value. For example, "gender" is a variable that has 2 values, male and female. Recently there have been even more categories added to this variable. Ex) Male, Female, Non-Binary, Trans, and Refuse to State.

Choose the BEST definition of Real Limits.

are the true extensions of the lower apparent limit minus 0.5 unit and the upper apparent limit plus 0.5 unit.

A distribution of scores is negatively skewed. Which is the most probable order for the three measures of central tendency?

mean = 25, median = 45, mode = 65

The last point on a cumulative frequency polygon represents the _____________________ of the last interval which is equal to ___. It is left hanging in hte air

cumulative frequency, n

The mode is the

most frequent score.

Identify the following example by its level of measurement. ex. Hair color (red, brown, black, blond, etc.)

nominal

Identify the following example by its level of measurement. ex. Marital status

nominal

Identify the following example by its level of measurement. ex. The number of people in your class who have red, blond, black, and brown hair

nominal

Identify the following example by its level of measurement. ex. Zipcodes

nominal

Identify the following example by its level of measurement. ex. Level of stress on a scale 1 (not at all) to 5 (very)

interval or ratio

Identify the following example by its level of measurement. ex. Time

interval or ratio

Frequency polygons are NOT used with

interval scales of measurement

Identify the following example by its level of measurement. ex. Letter grade on exam

ordinal

Identify the following example by its level of measurement. ex. World ranking of sudoku masters

ordinal

Identify the following example by its level of measurement. ex. Your rankings of the 10 best movies of last year

ordinal

Measures of central tendency are

scores that represent the center of a distribution.

Line graphs should be avoided when:

the variable on the X-axis is a qualitative variable

According to the text, Pie charts are NOT effective for displaying the relative frequencies of a______ number of categories. They ARE recommended, however, when you have a _______ number of categories

Large/Small

Which of the following statements is TRUE about Stem and Leaf Diagrams?

Allows us to display raw data visually

In a frequency distribution, where is the frequency plotted?

Along the ordinate

In a histogram, frequencies are represented by_______

Bars

For the following stem and leaf plot, how many numbers are there between -2 and -1? 4|33 3|56 2|00456 1|00134 0|1245589-0|0679-1|005559-2|7

1

A researcher conducted a study on the number of hours students studied for an exam. The data for the small sample are below: Hours Studied 2 3 3 2 5 Calculate the standard deviation for this data

1.225

Given the following values for a sample of 5 scores, compute the sample standard deviation Sum of X = 12.9 Sum of X2 = 40.09 n=5

1.305

For the following stem and leaf plot, how many numbers are there between 3 and 4? 4|33 3|56 2|00456 1|00134 0|1245589-0|0679-1|005559-2|7

2

Given the following values for a sample of 10 scores, compute the sample variance. Sum of X-= 524 Sum of X2 = 32836 n = 10

597.6

Compute the range of the following five scores: 5, 18, 24, 65, 89, and 104

99

Compute the cumulative percent using the data below

Cumulative Percent 100 85 50 50 50 40 25 2.5

A frequency histogram bars are plotted using apparent limits

False

A frequency histogram bars are plotted using apparent limits.

False

A variable is any event or characteristic that can assume only one value.

False

Bar charts are NOT particularly useful for showing change over time.

False

Measures of central tendency represent the center of a distribution

False

Populations can only be large groups of 1,000+ subjects

False

Raw data are numbers that have been collected and organized/summarized.

False

Stem and leaf displays are NOT good for comparing two groups.

False

Stem and leaf displays are good for comparing three groups.

False

Stem and leaf displays are good for comparing three groups:

False

The best measure of central tendency for skewed distributions is the mean.

False

The median is the mathematical center of the distribution.

False

The rule of thumb to creating grouped frequency distributions is to create between 5 and 10 class intervals and adjust the size of the intervals accordingly.

False

The text recommends that bar charts are better at showing means than box plots

False

The zero skewed distribution has one tail.

False

The newspaper reports that higher rates of sunburn and ice cream consumption correspond. Does that mean that eating ice cream can put you at risk of sunburn? What might be the reason behind this phenomenon?

In summer both ice cream consumption and rates of sunburn increase

Raw data

Raw data are the scores or numbers that have been collected but not organized or summarized

A sociologist studying the prevalence of alcohol use among seniors in a particular high school asked 45 of these youth how many drinks they had consumed in the last week. Convert the following frequency distribution of responses (number of drinks) into a grouped frequency distribution containing four class intervals. What is the the real limits and apparent limits of each class interval?

Real Limits: 0-2.5, 2.5-5.5, 5.5-8.5, 0-2, 3-5, 6-8 Apparent Limits:

You are a research director of a large multinational research firm, and you are interested in measuring the relative effectiveness of two different senior research training programs. You counted the number of positive responses from a survey given at the end of each training. Identify the INDEPENDENT VARIABLE.

The independent variable is effectiveness of two different senior research training programs.

According to the text, Pie charts are effective for displaying the relative frequencies of a______ number of categories. They are not recommended, however, when you have a _______ number of categories.

Small, large

What is the correct definition of parameters?

Statistics that describe population values such as averages

You are a sociologist who is interested in studying the difference in the level of happiness between groups of people at different socioeconomic levels. Identify the INDEPENDENT VARIABLE.

The independent variable is socioeconomic levels

In a positively skewed distribution of midterm scores, Sue scored at the mean, Sally scored at the median, and Silvia scored at the mode. Who had the highest midterm score?

Sue

A social scientist is interested in measuring the difference in social interaction between people in groups of three compared to people in groups of five. What is the DEPENDENT variable?

The dependent variable is difference in social interaction.

You are a research director of a large multinational research firm, and you are interested in measuring the relative effectiveness of two different senior research training programs. You counted the number of positive responses from a survey given at the end of each training. Identify the DEPENDENT VARIABLE.

The dependent variable is number of positive responses at the end of each training day.

You are a sociologist who is interested in studying the difference in the level of happiness between groups of people at different socioeconomic levels. Identify the DEPENDENT VARIABLE.

The dependent variable is the level of happiness

A histogram is a type of

bar graph

The most commonly used measure of central tendency is the

the mean

Student A knows that frequency polygons portray the same information as a frequency histogram. However, student A is unsure what single point measurement to use to represent the class interval. What measurement is used to represent the class interval in a frequency polygon?

the midpoint

The mode of a grouped frequency distribution is equal to

the midpoint of the most frequent interval

Choose the true statement that completes the following sentence: The y-axis is ______________________________

the ordinante and where the dependent variable in plotted