Chapter One- Introduction to Statistics

Question 1

What is data?

Answer 1

Data are collections of observations, such as measurements, genders, or survey responses.

Question 2

What is datum?

Answer 2

A single data value

Question 3

What is statistics?

Answer 3

Statistics is the science of planning studies and experiments; obtaining data; and then organizing, summarizing, presenting, analyzing, and interpreting those date and then drawing conclusions based on them.

Question 4

What is a population?

Answer 4

A population is the complete collection of ALL measurements or data that are being considered.

Question 5

What is a census?

Answer 5

A census is the collection of data from EVERY member of the population.

Question 6

What is a sample?

Answer 6

A sample is a sub-collection of members from a population.

Question 7

What is a parameter?

Answer 7

A parameter is a numerical measurement describing some characteristic of a population.

Question 8

What is a statistic?

Answer 8

A statistic is a numerical measurement describing some characteristic of a sample.

Question 9

What does Quantitative data consist of?

Answer 9

Quantitative data consist of numbers representing counts or measurements.

Question 10

What does Categorical data consist of?

Answer 10

Categorical data consist of names or labels that are NOT numbers representing counts or measurements.

Question 11

When does Discrete Data result?

Answer 11

Discrete Data result when the data values are quantitative and the number of values is finite or “countable”. (If there are infinitely many values, the collection of values is countable if it is possible to count them individually, such as the number of tosses of a coin before getting tails.

Question 12

When does Continuous Data result?

Answer 12

Continuous Data result from infinitely many possible quantitative values, where the collection of values is not countable. (That is, it is impossible to count the individual items because at least some of them are on a continuous scale, such as the lengths from 0cm to 12cm.)

Question 13

Define “ Nominal Level of Measurement”.

Answer 13

The Nominal Level of Measurement is characterized by data that consist of names, labels, or categories only. The data cannot be arranged in an ordering scheme (such as low to high).

Question 14

Define “ Ordinal Level of Measurement”.

Answer 14

Data are at the Ordinal Level of Measurement if they can be arranged in some order, but differences (obtained by subtraction) between data values either cannot be determined or are meaningless.

Question 15

Define “Interval Level of Measurement”.

Answer 15

Data are at the Interval Level of Measurement if they can be arranged in order, and differences between data values can be found and are meaningful. Data at this level do not have a natural zero starting point at which none of the quantity is present.

Question 16

Define “ Ratio Level of Measurement”.

Answer 16

Data are at the Ratio Level of Measurement if they can be arranged in order, differences can be found and are meaningful, and there is a natural zero starting point (where zero indicates that NONE of the quantity is present). For data at this level, difference and ratios are both meaningful.

Question 17

Define “Observational Study”.

Answer 17

In an observational study, we observe and measure specific characteristics, but we don’t attempt to modify the subjects being studied.

Question 18

Define “Experimental Study”

Answer 18

In an experiment, we apply some treatment and then proceed to observe its effects on the subjects, (subjects in experiments are called experimental units)

Question 19

What is “random sampling”?

Answer 19

Random Sampling is when each member of the population has an equal chance of being selected. Computers are often used to generate random telephone numbers.

Question 20

What is “simple random sampling”?

Answer 20

Simple Random Sampling is when a sample of N subjects is selected in such a way that every possible sample of the same size N has the same chance of being chosen.

Question 21

What is “systematic sampling”?

Answer 21

Systematic Sampling is when you select a starting point, then select every kth (such as every 50th) element in the population.

Question 22

What is “convenience sampling”?

Answer 22

Convenience sampling is when you use results that are easy to get.

Question 23

What is “stratified sampling”?

Answer 23

Stratified sampling is when you subdivide the population into at least two different subgroups (or strata) so that subjects within the same subgroup share the same characteristics) such as gender or age bracket), then draw a sample from each subgroup.

Question 24

What is “cluster sampling”?

Answer 24

Cluster sampling is when you divide the population into sections (or clusters), then randomly select some of those clusters, and then choose ALL members from those selected clusters.

Question 25

In a cross sectional study, data…

Answer 25

In a cross sectional study, data are observed, measured, and collected at one point in time, not over a period of time.

Question 26

In a retrospective (or case control) study data are collected from…

Answer 26

data are collected from a past time period by going back in time (through examination of records, interviews, and so on).

Question 27

In a prospective (or longitudinal or cohort) study data are collected in…

Answer 27

data are collected in the future from groups that share common factors (such as groups area called cohorts).

Question 28

Define “randomization”.

Answer 28

Randomization is used when subjects are assigned to different groups through a process of random selection.

Question 29

Define “replication”

Answer 29

Replication is the repetition of an experiment on more than one subject.

Question 30

Define “Blinding”

Answer 30

Blinding is in effect when the subject doesn’t know whether he or she is receiving a treatment or a placebo.

Question 31

Define “placebo effect”

Answer 31

Placebo effect, occurs when an untreated subject reports an improvement in symptoms.

Question 32

Define “double blind”

Answer 32

Double blind means that blinding occurred at two levels: the test subject does not know if they are given the drug or placebo and the doctors who give the drug also do not know if it is the drug or a placebo

Question 33

Define “confounding”

Answer 33

Confounding occurs in an experiment when the investigators are not able to distinguish among the effects of different factors.

Question 34

What experiment design is being used when we form a block of women and a block of men and within each block, randomly select subjects to be treated?

Answer 34

Randomized block design

Question 35

What experiment design is being used when we use randomness to determine who gets the treatment and who gets the placebo?

Answer 35

Completely randomized experimental design

Question 36

What experiment design is being used when we get measurements from the same subjects before and after some treatment?

Answer 36

Matched pairs design

Question 37

When does a sampling error occur?

Answer 37

A sampling error occurs when the sample has been selected with a random method, but there is a discrepancy between a sample result and the true population result; such an error results from chance sample fluctuations.

Question 38

A non sampling error is the result of?

Answer 38

Is the result of human error, including such factors as wrong data entries, computing errors, questions with biased wording, false data provided by respondents, forming biased conclusions, or applying statistical methods that are not appropriate for the circumstances.

Question 39

A random sampling error is the result of?

Answer 39

Is the result of using a sampling method that is not random, such as using a convenience sample or voluntary response sample.