Session #6 Flashcards Preview

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Flashcards in Session #6 Deck (40):
1

what are the two types of quantitative data?

continous
discrete

2

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

continuous

ex: shear strength of porcelain

3

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

discrete

ex: possible number of teeth someone has

4

what are the two types of categorical data?

nominal
ordinal

5

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

nominal

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

6

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

ordinal

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

7

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

mean

8

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

standard deviation

9

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

correlation

10

the value of a correlation coefficient lies between what numbers?

-1 and 1

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

11

the fraction of variation in Y explained by X

square of the correlation

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

12

an explanation of certain observations

hypothesis

13

what do we use hypothesis testing for?

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

14

what is the null hypothesis?

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

15

what is the alternative hypothesis?

-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

16

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

H0 interpretation

17

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

Ha interpretation

18

type 1 error

rejecting the null hypothesis that is actually true in the population

19

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

-o.o5
-the max chance (5%) of incorrectly rejecting the null hypothesis when it is actually true

20

type II error

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

21

beta

the probability of type II error

22

power

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

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

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

24

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

confidence interval

most common = 95%

25

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

t-test

26

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

one-sample t-test

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)

matched-pair t-test

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

chi-squared test

29

statistical method that allows for comparison of several population means

ANOVA

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

30

what type of statistic does an ANOVA test use?

F-statistic

31

Determining if findings are important from a clinical standpoint

clinical significance

32

probability that chance is responsible of an observed difference

statistical significane

33

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

no

34

what are the main limitations of statistical inference?

-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

35

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

bias

36

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

selection bias

37

errors in procedures for gathering relevant info

info bias

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

confounding variable

39

what two things make a variable a confounder?

-it is a known risk factor of the outcome
-it is associated with the exposure but is not the result of the exposure

40

is confounding an "all or none" phenomenon?

no