PBSI 301 - Exam 1 TAMU

scale of measurement

different ways of categorizing measurement outcomes: nominal, ordinal, interval, and ratio

nominal level of measurement

the most gross level of measurement by which a variable's value can be placed in one and only one category

ordinal level of measurement

a level of measurement that places a variable's value into a category and assigns that category an order with respect to other categories

interval level of measurement

a level of measurement that places a variable's values into categories that are equidistant from each other, as when points are evenly spaced along a scale

ratio level of measurement

a level of measurement defined as having an absolute zero

class interval

a fixed range of values, used in the creation of a frequency distribution

histogram

a graphical representation of a frequency distribution that uses bars of different heights to show the number of values that fall within each class interval

ogive

a visual representation of a cumulative frequency distribution

scattergram

a plot of paired data points on an x-axis and a y-axis, used to visually represent a correlation

correlation matrix

a table showing correlation coefficients among more than two variables

coefficient of determination

the amount of variance in one variable that is accounted for by the variance in another variable

coefficient of alienation

the amount of variance in one variable that is not accounted for by the variance in another variable

partial correlation

a numerical index that reflects the relationship between two variables with the removal of the influence of a third variable (called a mediating or cofounding variable)

dependent variable

the outcome variable or the predicted variable in a regression equation

independent variable

the treatment variable that is manipulated or the predictor variable in a regression equation

true score

the score that, if it could be observed, would reflect the actual ability or behavior being measured

error score

the part of a test that is random and contributes to the unreliability of a test

parallel forms reliability

a type of reliability that examines consistency across different forms of the same test

internal consistency reliability

a type of reliability that examines whether items on a test measure only one dimension, construct, or area of interest

interrater reliability

a type of reliability that examines whether observers are consistent with one another

content validity

a type of validity that examines how well a test samples a universe of items

criterion validity

a type of validity that examines how well a test reflects some criterion that exists in either the present (concurrent) or the future (predictive)

concurrent criterion validity

how well a test outcome is consistent with a criterion that exists in the present

predictive criterion validity

how consistent a test outcome is with a criterion that occurs in the future

construct validity

how well a test reflects an underlying idea, such as intelligence or aggression

what are science's 3 basic goals and how does statistics help accomplish these goals?

description, prediction and explanation

why do outliers not impact the median?

because the median cares about the number of cases

what are some examples of categorical data?

ethnicity, major, eye color, experimental condition

what are some examples of continuous data?

height, weight, age, self-esteem (all numbers between two endpoints are possible scores)

what scale falls under categorical data?

nominal scale

what scales fall under continuous data?

ordinal, interval and ratio scale

is nominal level of measurement mutually exclusive?

yes

what is an example of a nominal level of measurement?

eye color and political affiliation

what is an example of an ordinal level of measurement?

ranking candidates for a job; gold, silver, bronze metals at the Olympics

what is an example of an interval level of measurement?

celsius and fahrenheit

what is an example of a ratio level of measurement?

zero molecular movement, zero light, zero answers correct

what does categorical data measure?

mode

what does continuous data measure?

median or mode

when do you use mode in categorical or nominal data?

when the data and values only fit into one category

when do you use the median in continuous data?

when you have extreme scores

when do you use the mean in continuous data?

when the data do not include extreme scores or outliers

categorical data

data that sorts people or things into categories

continuous data

data measured on a continuum

identify this scale of measurement: Accuracy in spelling 20 words

ratio

identify this scale of measurement: hair color; black, brown, blonde, other

nominal

identify this scale of measurement: dress or clothing size 0-20

interval

identify this scale of measurement: likert scale; 1 = agree to 10 = disagree

ordinal

identify this scale of measurement: rating scale; -3 = Mad to +3 = Happy

ordinal

identify this scale of measurement: reaction time in seconds

ratio

identify this scale of measurement: marital status; single, married, divorced

nominal

identify this scale of measurement: US shoe sizes 5 to 15

interval

identify this scale of measurement: shoe sizes based on cm or inches

ratio

different samples may have different degrees of variability for the same variable

true

example of different samples having different degrees of variability for the same variable

2 different classes taking the same test / same central tendency, but different variability

what are the problems with range?

ignores the middlemost values and considers only the most extreme scores

what does a small/low SD value indicate?

most data points tend to be closer to the mean

what does a large/high SD value indicate?

most data points tend to be far away from the mean

what are the ten ways to make a great figure?

1. minimize the junk

2. plan before you create

3. say what you mean; mean what you say

4. label everything

5. communicate one idea

6. keep things balanced

7. maintain the scale in the graph

8. simple is best, less is more

9. limit the number of words

10. the chart alone should convey what you want to say

what is a frequency distribution?

a frequency distribution is a method of tallying and representing the number of times a certain score occurs

what is a histogram?

visual representation of a frequency distribution

what is a frequency polygon?

shows a continuous line that represents the frequencies of scores within a class interval

what is kurtosis?

how peaked vs. flat a distribution is

what is platykurtic?

low kurtosis, flat, more variability

what is leptokurtic?

high kurtosis, peaked, less variability

.5 to 1 correlation indicates what type of relationship?

strong relationship

.4 correlation indicates what type of relationship?

moderate to strong relationship

.3 correlation indicates what type of relationship?

moderate relationship

.2 correlation indicates what type of relationship?

weak to moderate relationship

0 to .1 correlation indicates what type of relationship?

weak or no relationship

when will correlation coefficients be reduced in value and not capture the true relationship between variables?

when there is a restriction of range

does outliers have a big influence on correlation coefficients?

yes

when does a restriction of range occur?

when most subjects have similar scores on one of the variables being correlated or there is an artificial boundary on one end of one variable

r sqaured is what?

coefficient of determination

what is the coefficient of determination?

the percentage of variance in one variable that is accounted for by the variance in the other variable

1 - r squared is what?

coefficient of alienation or nondetermination

what is the coefficient of alienation or nondetermination?

the amount of unexplained variance

correlation expresses what between two or more variables?

association NOT causality

self-report measure

asking people questions about themselves in a questionnaire / how many caffeinated beverages have you consumed today?

observation/behavioral measure

recording observable behaviors / operationalizing cleanliness by quantifying how much dust someone has on their furniture

physiological measure

record biological data / operationalizing whether someone can distinguish between two different speech sounds by examining his or her brain responses to those sounds

what two things do you want when interpreting reliability coefficients?

the reliability coefficient to be positive and not negative and reliability coefficients to be as large as possible