Ch.12 Correlation and Descriptive statistics

A researcher finds that out of 400 pet owners surveyed, 250 own only a dog, 125 own only a cat, and 25 own a bird. Which measure of central tendency is the most appropriate for this data? A. Mean B. Standard deviation C. Mode D. Median

C. Mode

Bar Graphs

Represents the same information as pie charts

correlation coefficient

a statistic that describes how strongly variables relate - -1.00 to 1.00

Which one of the following scales of measurement lacks numeric properties? a. Nominal b. Ordinal c. Interval d. Ratio

a. Nominal

mean

adding all scores and dividing by the number of scores -appropriate for an interval, ratio scale

regression equation

are calculations used to predict a person's score on one variable when that person's score on another variable is already known

In studying the effect of temperature on ice cream cone sales, a researcher could record the number of ice cream Cones sold on cold vs. Hot days. The researcher would be most interested in a) comparing group performance b) comparing group means c) correlating scores d) comparing the type of ice cream sold

b) comparing group means

What is the difference between interval and ratios scale? A ratio scale__________ while an interval scale does not. a. Uses equal intervals b. Has an absolute zero c. indicates order d. gives numerical information

b. Has an absolute zero

A host of a home repair program rates the difficulty of various home improvement projects. He assigns the level of difficulty by using hammers: three for very difficult, two for moderate, one for easy. This is an example of a(n)____________ scale. a. Nominal b. Ordinal c. Interval d. Ratio

b. Ordinal

A Teacher writes the results of a test on the board: seven students received A's, 10 students received B's, 18 students received C's, for students received D's, and student received an F. In statistical terms this is a. Measure of central tendency b. Measure of variability c. Frequency distribution d. Correlation table

c. Frequency distribution

Which one of the following is NOT a measure of central tendency? a. Mean b. Median c. Meridian d. Mode

c. Meridian

All Correlation coefficient a. are positive b. are negative c. range from -1.00 + 1.00 d. use interval data

c. range from -1.00 + 1.00

The range and standard deviation are both a. Measures the variability b. Descriptive statistics c. Useful ways to summarize data d. All of these

d. All of these

Which one of the following would be an appropriate measure of central tendency to summarize original data? a. Mean b. Median c. Correlation d. Any of these would be appropriate

d. Any of these would be appropriate

The correlation coefficient a. Indicates the amount of spread of scores in the distribution b. Is a measure of central tendency c. Is a measure variability d. Is a statistic that describes how strongly variables are related to one another

d. Is a statistic that describes how strongly variables are related to one another

A predictor variable is generally analogous to a(n)_______________ variable in the experimental method.

independent

Standard deviation

indicates the average deviation of scores from the mean

frequency distribution

indicates the number of individuals who receive each possible score on a variable.

Ordinal Scale

levels exhibit minimal quantitative properties. -you can rank the order the levels of the variable

restriction range

occurs when the individuals in your sample are very similar on the variable you are studying

partial correlation

provides a way of statistically controlling third variables.

mode

the most frequent score. - appropriate for a nominal scale

variance

the square of the standard deviation - used when set of standard deviation scores is too small

pie charts

useful for representing nominal scale intervals

histogram

uses bars to display a frequency distribution for a quantitative variable.

scatter plot

when each pair of scores is plotted as a single point on a chart or diagram

Deceptive statistics

Allow researchers to make precise statements about the data. two statistics are needed to describe the data. a number describes central tendency, how participants scored over all, variability, and distribution of scores.

Nominal Scale

Variables have no numerical, quantitative properties. The levels are simply different categories or groups.

frequency polygon

a line used to represent the distribution of frequencies of scores. This is most useful when the data represents interval or ratio scales

variability

a measure of variability is a number that characterizes the amount of spread in a distribution of scores.

Henry signs that for automobile owners, as the price of gasoline increases, the amount of miles they drive in a week decreases. This finding would suggest____________ relationship a. A positive b. A negative c. A curvilinear d. No

b. A negative

Any set of scores may be measures of ____________ and _____________. a. Chance Variance; Error Variance b. Central Tendency; Variability c. Independent variables; Dependent variables d. Probability; significance

b. Central Tendency; Variability

Ratio Scale

quantitative properties - have both equal intervals and an absolute zero point that indicates the absence of the variable being measured

Interval Scale

quantitative properties -the intervals between the levels are equal in size

effect size

refers to the strength of the association between variables

central tendency

tells us what the sample as a whole, or on the average, is like. there are three measures: mean, median, mode.

range

the difference between the smallest data point and the largest data point

median

the score that divides the group in half -appropriate for an ordinal scale

Brewster measures the height and age of four and five year old.To his surprise, he finds no correlation between height and age. What is most likely responsible for his results? A. He has restricted the range of the variables. B. There is too much variability in the sample to accurately calculate a correlation C. A curvilinear relationship exists between the variables. D. Age and height are not related.

A. He has restricted the range of the variables.