Test 2

Question 1

Double-Blind Experiments

Answer 1

Neither the patients nor the supervisors know who is receiving a placebo

Question 2

Block Design

Answer 2

Organize subjects into groups that match the different strata of the population and assign them randomly to different treatments in each block

Question 3

Lurking Variables (in linking religiosity to longevity)

Answer 3

gender, education, physical mobility, ethnicity, age

Question 4

Randomized Comparative Experiment

Answer 4

Assign subjects RANDOMLY to a TREATMENT GROUP and a CONTROL GROUP. Treat the subjects in the treatment group but not those in the CONTROL GROUP (or treat the latter with a PLACEBO). Compare the effects and decide whether there is a difference between the two group that is STATISTICALLY SIGNIFICANT.

Question 5

Measuring

Answer 5

MEASUREMENTS assign numerical values to VARIABLES that are descriptive of certain PROPERTIES of (statistical) individuals. Measurements are often performed by means of INSTRUMENTS that employ specific UNITS. A variable is a VALID measure of a property in it is relevant or appropriate as a representation of that property.

Question 6

Rates; Counts

Answer 6

___ are frequently more valid or meaningful measures than simple ___.

Question 7

Predictive Validity

Answer 7

The most useful form of validity

Question 8

Examples of measurements

Answer 8

length, time, college readiness, highway safety, unemployment, intelligence

Question 9

Unemployment rate

Answer 9

=number of people unemployed
________________________________
number of people in the labor force

Question 10

Predictive Validity

Answer 10

Predicting success in college by using SAT scores.
Predicting the weather from current conditions.
Predicting statistical particle behavior by means of quantum descriptions.

Question 11

Measurement Errors

Answer 11

Measured value = true value + bias + random error

Question 12

Errors; bias; randomness

Answer 12

___ in measurement can be due to ___ or ___.

Question 13

Reliable

Answer 13

If the random error is small, the measurement is said to be ___.

Question 14

Reliability

Answer 14

can be improved by taking averages over several repeated measurements

Question 15

Bias

Answer 15

can be reduced by using better instruments (atomic clocks instead of mechanical or quartz-based clocks).

Question 16

Categorical variable

Answer 16

divides a given population into different groups or categories (distribution is commonly displayed by a bar graph or pie chart)

Question 17

Quantitative variable

Answer 17

variable that takes numerical values (the change over time may be displayed by a line graph)

Question 18

Distribution; symmetric

Answer 18

a ___ is ___ if the parts to the right and left of the center approximately mirror each other

Question 19

Distribution skewed to the right

Answer 19

the parts to the rights of the center extend farther than the parts to the left

Question 20

Distribution skewed to the left

Answer 20

the parts to the left of the center extend farther than the parts to the right

Question 21

Describing Distributions

Answer 21

the median, quartiles, maximum/minimum, mean/average, variance, and standard deviation

Question 22

Overall pattern; deviations

Answer 22

in any graph of data, look for an ___ and also for striking ___ from that pattern

Question 23

Outlier

Answer 23

An ___ in any graph of data is an individual observation that falls outside the overall pattern

Question 24

mean

Answer 24

= sum of values
____________________
number of values

Question 25

Sample variance

Answer 25

the sum of a set of numbers divided by n-1 (n=amount of numbers in the set)

Question 26

Sample standard deviation

Answer 26

finding the sample standard deviation s by taking the square root of the variance