Quiz 1

Question 1

Define population

Answer 1

The set of observations/units that we would obtain if observing/sampling went on indefinitely

Question 2

Define Sample

Answer 2

subset of observed observations/units

Question 3

Define Design

Answer 3

the procedure in planning/collecting data,

Question 4

Define Statistics

Answer 4

the art and science of designing studies and analyzing the data that those studies produce

numerical summary of a sample taken from the population

Question 5

What are the four components of statically problem

Answer 5

1. formulate a statistical question
2. collect data
3. analyze data
4. interpret results

Question 6

Define parameter

Answer 6

numerical summary of the population

Question 7

Define descriptive statistics

Answer 7

methods for summarizing the collected data

Question 8

Define inferential statistics

Answer 8

methods of making decisions or predictions about a population, based on data obtained from a sample of that population

Question 9

What is meant by the distribution of a variable

Answer 9

description of the relative numbers of times each possible outcome will occur in a number of trials

Question 10

What do frequency and relative frequency represent in a distribution

Answer 10

to serve as a way to summarize the measurements in categories of a categorical value

Question 11

Define Histogram

Answer 11

a graph that uses bars to portray the frequencies or the relative frequencies of the possible outcomes for a quantitative variable

Question 12

What does a dot plot show

Answer 12

each dot shows an observation, placed above the value

Question 13

What is the example of variance

Answer 13

s^2 = (x_1 − ¯x)^2 + (x^2 − ¯x)^2 + · · · + (x_n − ¯x)^2 OVER n-1

∑(x − ¯x)^2
OVER n − 1

Question 14

What is the example for standard deviation

Answer 14

s = √(x_1 − ¯x)^2 + (x^2 − ¯x)^2 + · · · + (x_n − ¯x)^2 OVER n − 1

√∑(x − ¯x)^2 OVER n − 1

Question 15

What are the 3 types of bias and the definition of each one

Answer 15

Sampling- undercoverage of some types of units

Nonresponse- failure of some types of units to respond or be observed

Response- inaccurate responses/observations from selected and responding units

Question 16

What is the z-score equation

Answer 16

z = x − ¯x OVER S

Question 17

What is the five number summary

Answer 17

1. The minimum value.
2. The first quartile (Q1, i.e., the median of the lower half of the distribution).
3. The second quartile (Q2, i.e., the median).
4. The third quartile (Q3, i.e., the median of the upper half of the distribution).
5. The maximum value.

Question 18

What is the range

Answer 18

Measure of variability defined as maximum value − minimum value

Question 19

What is the interquartile range

Answer 19

Measure of variability defined as Q3 − Q1

Question 20

What is the mean equation

Answer 20

¯x = x_1 + x_2 + · · · + x_n OVER n

=∑x OVER n

Question 21

Define outlier

Answer 21

an unusually large or small observation of a quantitative variable relative to the distribution of that variable in a given sample/population

Question 22

What is the difference between Bias and Random Error

Answer 22

Bias- tendency to overestimate or underestimate a parameter

Random- Variation in the error of estimation from sample to sample due to non-systematic sources

Question 23

Define error of estimation

Answer 23

the difference between a parameter and a statistic when using the statistic to estimate the parameter

Question 24

What is random sampling

Answer 24

units included in the sample by chance. Eliminates sampling bias, but not non-response or response bias

Question 25

What kind of bias is eliminated by random sampling

Answer 25

sampling bias, but not non-response or response bias

Question 26

What is the difference between Response and Explanatory Variable

Answer 26

Response- distribution of interest is that of the response variable

Explanatory- each value of the explanatory variable defines a distinct real or hypothetical distribution of the response variable

Question 27

Define Experiment

Answer 27

explanatory variable is under the control of the researchers in the sense that treatments are assigned to experimental units by researchers

Question 28

Define observational study

Answer 28

explanatory variable is not under the control of the researchers. Units are “assigned” to treatments by some other mechanism

Question 29

Define lurking variable

Answer 29

a usually unobserved variable associated with the explanatory and response variables and influences the apparent association between those variables

Question 30

Define randomization

Answer 30

assignment of treatments to experimental units in an experiment in random, creating a randomized experiment

Question 31

How does randomization deal with the lurking variable problem

Answer 31

lurking variables can arise after randomization

Question 32

What is statistically significant

Answer 32

the results are decidedly not due to chance alone

Question 33

What is a crossover design

Answer 33

the special cade of a matched-pairs design where a single unit is observed twice

Question 34

What is a completely randomized design

Answer 34

each experimental unit is assigned a treatment randomly

Question 35

What is a matched-pairs design

Answer 35

treatments are assigned to each unit in a pair

Question 36

What is simple random sampling

Answer 36

every sample of n units has an equal chance of being selected

Question 37

Identify the outlier for a bell-shaped distribution

Answer 37

any observation with a z-score that is large in absolute value

say, |z|>2 or |z|>3

Question 38

Identify the outlier for 1.5 x IQR criterion

Answer 38

a distribution of any shape we can maybe use the rule that if then the observation is an outlier

x>Q_3 + 1.5 x IQR or x < Q_1 -1.5 x IQR