Session #6

Question 1

what are the two types of quantitative data?

Answer 1

continous

discrete

Question 2

type of quatintative data in which all values are possible in a range

Answer 2

continuous

ex: shear strength of porcelain

Question 3

type of quantitative data in which only certain valuess are possible in a range

Answer 3

discrete

ex: possible number of teeth someone has

Question 4

what are the two types of categorical data?

Answer 4

nominal

ordinal

Question 5

type of categorical data where data falls into category, but no order to data

Answer 5

nominal

ex. presence/absence of oral cancer, or race/ethnicity

Question 6

type of categorical data where that has a specific order to it

Answer 6

ordinal

how often do you brush your teeth? (never, seldom, always)

Question 7

which is more sensitive to extreme values, the mean or the median?

Answer 7

mean

Question 8

measure of how much the individual data points vary around the MEAN

Answer 8

standard deviation

Question 9

describing if there is a linear relationship btw an independent variable (X) and a dependent variable (Y)

Answer 9

correlation

Question 10

the value of a correlation coefficient lies between what numbers?

Answer 10

• 1 and 1

* the closer (r) is to 1 or -1 the stronger the relationship

Question 11

the fraction of variation in Y explained by X

Answer 11

square of the correlation

the higher the r-squared the better the fit of the regression line

Question 12

an explanation of certain observations

Answer 12

hypothesis

Question 13

what do we use hypothesis testing for?

Answer 13

to tell if what we observe in the population is consistent with the hypothesis

Question 14

what is the null hypothesis?

Answer 14

states that there is NO DIFFERENCE btw two groups being compared or NO EFFECT of a product or intervention

Question 15

what is the alternative hypothesis?

Answer 15

• this is the one the researcher thinks is the “truth”
• states that THERE IS A DIFFERENCE btw two groups being compared or an effect of a product or intervention

can be directional or non-directional

Question 16

the population mean for group 1 is the same as the population mean for group 2

Answer 16

H0 interpretation

Question 17

the population mean for group 1 is different than the population mean for group 2

Answer 17

Ha interpretation

Question 18

type 1 error

Answer 18

rejecting the null hypothesis that is actually true in the population

Question 19

the level of statistical significance (alpha) is commonly set to _____ and is interpreted as what?
***this is only in type I errors

Answer 19

• o.o5

- the max chance (5%) of incorrectly rejecting the null hypothesis when it is actually true

Question 20

type II error

Answer 20

failing to reject the null hypothesis that is actually false in the population

Question 21

beta

Answer 21

the probability of type II error

Question 22

power

Answer 22

1-B and is related to the sample size used in the study

Question 23

the probability, assuming that the null hypothesis is true, of seeing an effect as extreme or more extreme than that in the study by chance

Answer 23

p-value

• reject the null hypothesis is P-value less than or equal to alpha
• fail to reject if P-value is more than alpha

—-the higher the p-value, the more leeway you are giving yourself to be wrong by chance

Question 24

a range of values about a sample stat that we are confident that the true pop parameter lies

Answer 24

confidence interval

most common = 95%

Question 25

statistical test that can be used to determine whether the mean value of continuous outcome variable differs significantly between two independent groups

Answer 25

t-test

Question 26

type of t-test that can be used when the outcome variable of interest is only being examined in one group

Answer 26

one-sample t-test

Question 27

type of t-test that can be used when subjects are matched in pairs and their outcomes are compared within each matched pair (including where observations are taken on the same subjects before and after giving and intervention)

Answer 27

matched-pair t-test

Question 28

when examining categorical data, this test can be used to compare the proportion of subjects in each of two groups who have a dichotomous outcome

Answer 28

chi-squared test

Question 29

statistical method that allows for comparison of several population means

Answer 29

ANOVA

***IS USED FOR CONTINUOUS VARIABLES WITH MORE THAN TWO GROUPS

Question 30

what type of statistic does an ANOVA test use?

Answer 30

F-statistic

Question 31

Determining if findings are important from a clinical standpoint

Answer 31

clinical significance

Question 32

probability that chance is responsible of an observed difference

Answer 32

statistical significane

Question 33

does a p-value say anythings about clinical relevance or quality of a study?

Answer 33

no

Question 34

what are the main limitations of statistical inference?

Answer 34

• only tells about the role of chance or random error in making inference from your study population to the source populaiton
• does NOT tell about the role of bias or confounding
• STATISTICS DO NOT TELL YOU ABOUT CAUSALITY

Question 35

systematic error in design, conduct or analysis of a study that results in a mistaken estimate of an exposure’s effect on disease

Answer 35

bias

Question 36

systematic error in selecting subjects into one or more groups, such as cases and controls, or exposed or unexposed

Answer 36

selection bias

Question 37

errors in procedures for gathering relevant info

Answer 37

info bias

Question 38

situation in which a non-causal association btw a given exposure and an outcome is observed as a result of the influence of a third variable

Answer 38

confounding variable

Question 39

what two things make a variable a confounder?

Answer 39

• it is a known risk factor of the outcome

- it is associated with the exposure but is not the result of the exposure

Question 40

is confounding an “all or none” phenomenon?

Answer 40

no