Appendix - Statistics and Research Methods

Question 1

What are measures of central tendency?

Answer 1

They summarize or describe the entire set of data in some meaningful way (ex: mean, median, mode)

Question 2

What is a mean and how is it calculated?

Answer 2

It is the average of a sample. Add all of the individual components and divide by the number of components.

Question 3

What is a median and how is it calculated?

Answer 3

It is the middle number in a data set. The numbers are ordered and the middle number is found. For an even number of data, the median is the average of the two middle numbers.

Question 4

What are outliers?

Answer 4

numerical observations that are far removed from the rest of the observations

Question 5

What is a mode?

Answer 5

It is the most frequently recurring number in a data set. If there are no numbers that occur more than once, there is no mode. If there are multiple numbers that occur most frequently, each of those numbers is a mode.

Question 6

What are measures of variability?

Answer 6

measures of similarity and diversity within a date set (ex: range, standard deviation, percentile)

Question 7

What is a range?

Answer 7

It is the difference between the smallest and largest number in a sample.

Question 8

What is a standard deviation?

Answer 8

It is a measure of how much each individual number differs from the mean.

Question 9

What is meant by a low standard deviation?

Answer 9

Data points are all similar and close to the mean.

Question 10

What is meant by a high standard deviation?

Answer 10

Data points are spread out, farther from the mean.

Question 11

In a normal distribution, what percentage of data falls within 1 standard deviation from the mean?

Answer 11

34.1% above and 34.1% below (68.2% falls within 1 standard deviation of the mean)

Question 12

In a normal distribution, what percentage of data falls between one and two standard deviations from the mean?

Answer 12

13.6% above and 13.6% below (95.4% falls within 2 standard deviations of the mean)

Question 13

In a normal distribution, what percentage of data falls between two and three standard deviations?

Answer 13

2.1% above and 2.1% below (99.6% falls within 3 standard deviations of the mean)

Question 14

In a normal distribution, what percentage of data falls beyond three standard deviations?

Answer 14

0.2% above and 0.2% below (0.4% total beyond 3 standard deviations)

Question 15

What is a percentile?

Answer 15

They represent the area under the normal curve, increasing from left to right. It indicates the value/score below which the rest of the data falls. (ex: a score in the 75th percentile is higher than 75% of the rest of the scores). These are directly related to standard deviations.

Question 16

What is an independent variable?

Answer 16

the variable that is manipulated to determine its effect on the dependent variable

Question 17

What is a dependent variable?

Answer 17

a function of the independent variable, as the independent variable changes, so does the dependent variable

Question 18

What is statistical power?

Answer 18

the likelihood that you have enough subjects to accurately prove the hypothesis is true within an acceptable margin of error

Question 19

What is a random sample?

Answer 19

a subset of individuals from within a statistical population that can be used to estimate characteristics of the whole population

Question 20

What is sampling bias?

Answer 20

If a subset is not randomly selected, then this non-randomness might unintentionally skew the results.

Question 21

What is meant by the specific real area bias?

Answer 21

a sampling bias when people are selected in a specific physical space

Question 22

What is meant by the self-selection bias?

Answer 22

a sampling bias when people being studied have some control over whether or not to participate

Question 23

What is meant by pre-screening or advertising bias?

Answer 23

a sampling bias when volunteers are screened or when advertising is placed that might skew the sample

Question 24

What is meant by healthy user bias?

Answer 24

a sampling bias when the study population is likely healthier than the general population

Question 25

What is the t-test?

Answer 25

It is used to calculated whether the means of two groups are significantly different from each other statistically.

Question 26

When are two samples considered to be significantly different?

Answer 26

If the p-value is below +/- 0.05, it can be concluded with 95% confidence that the two sets of data are actually different.

Question 27

What is meant by a correlation coefficient (R/r) > 0?

Answer 27

Positive correlation: indicates a positive association between two variables (ex: if one increases, the other increases as well)

Question 28

What is meant by a correlation coefficient (R/r) < 0?

Answer 28

Negative correlation: indicates a negative association between two variables (ex: if one increases, the other decreases)

Question 29

What is meant by a correlation coefficient (R/r) = 0?

Answer 29

There is no linear relation between the two variable.

Question 30

Can causation be concluded from correlation?

Answer 30

no. never. no. no. no.

Question 31

What is reliability?

Answer 31

the degree to which a specific assessment tool produces stable, consistent, and replicable results

Question 32

What is test-retest reliability?

Answer 32

a measure of the reliability of an assessment tool in obtaining similar scores over time

Question 33

What is inter-rater reliability?

Answer 33

a measure of the degree to which two different researchers or raters agree in their assessment

Question 34

What is validity?

Answer 34

how well an experiment measures what it is trying to measure

Question 35

What are the 3 types of validity?

Answer 35

• internal
• external
• construct

Question 36

What is internal validity?

Answer 36

whether the results of a study properly demonstrate a causal relationship between the two variables tested (need random selection, random assignment to control/experimental groups, reliable instruments and processes, and safeguards against confounding factors)

Question 37

What are confounding factors?

Answer 37

hidden variables (those not directly tested for) that correlate in some way with the independent or dependent variable and have some sort of impact on the results

Question 38

What is external validity?

Answer 38

whether the results of a study can be generalized to other situations and other people (generalizability is limited to the independent variable)

• sample must be completely random
• all situational variables must be tightly controlled
• cause and effect relationships may not be generalizable to other settings, situations, or groups

Question 39

What is construct validity?

Answer 39

used to determine whether a tool is measuring what it is intended to measure (ex: does a survey ask questions clearly?)

Question 40

What is a randomized controlled trial?

Answer 40

• treatment group receives the treatment under investigationi
• control group receives no treatment, a placebo, or the current standard of care

Question 41

What is a double-blind experiment?

Answer 41

Neither the participants nor the researchers know which participants belong to the control group, as opposed to the test group.

Question 42

For experiments conducted on humans, what is the only real type of research that can product information about the effectiveness of treatment or therapy?

Answer 42

double-blinded randomized controlled trial