# Study sets matching "biostats"

Study sets

Classes

Users

probability=

4 steps of hypothesis testing

null hypothesis

random sampling variation

chance

1. making hypothesis... 2. set criteria for decision... 3. gather da…

there is no difference between your sample and the population…

all observed differences are due to chance

probability=

chance

4 steps of hypothesis testing

1. making hypothesis... 2. set criteria for decision... 3. gather da…

A contingency table is widely used to d…

what is the R code to build a contingen…

risk difference is defined as?

NNT or NNH can or cannot contain a deci…

the association between 2 categorical variables

table(data~independent,data~outcome)

a measure of the difference between two proportions... (a/(a+b))-…

cannot (don't have half a person)... round UP

A contingency table is widely used to d…

the association between 2 categorical variables

what is the R code to build a contingen…

table(data~independent,data~outcome)

Standard deviation

Prevalence

Incidence

Crude (Overall) Mortality Rate (CMR)

Used for symmetric measured data

# of ALL cases of a particular disease in a population... # case…

# of NEW cases of a disease in a population... # of new cases in…

# of deaths/ total population size... Measures the overall death…

Standard deviation

Used for symmetric measured data

Prevalence

# of ALL cases of a particular disease in a population... # case…

Hypothesis

Null hypothesis

Alternative hypothesis

Conditions

'a testable prediction drawn from a theory'

'the hypothesis has no effect (eg: the thing you're trying to…

'the hypothesis is correct and has an effect'

'total number of experimental groups in study'

Hypothesis

'a testable prediction drawn from a theory'

Null hypothesis

'the hypothesis has no effect (eg: the thing you're trying to…

Nominal data

Ordinal data

kinds of data in nonparametric tests

Types of tests associated with ordinal…

Comparing modes between groups

comparing medians between groups

Nominal and Ordinal

Mann-whitney U test... Wilcoxan Signed Rank test ... Kruskai wallis…

Nominal data

Comparing modes between groups

Ordinal data

comparing medians between groups

null hypothesis

alternative hypothesis

the likelihood of finding a difference…

how to calculate Confidence Interval

states that there is no difference

states that there is a difference

p value

=1-Type 1 error

null hypothesis

states that there is no difference

alternative hypothesis

states that there is a difference

Cross sectional study

Case- Control Study

Cohort Study

Phase 1

Data from a group of people to assess the frequency of a disea…

Compares a group with a disease to a group without the disease…

Compares a group with a given exposure or risk factor to a gro…

Small # of healty volunteers- is it safe?

Cross sectional study

Data from a group of people to assess the frequency of a disea…

Case- Control Study

Compares a group with a disease to a group without the disease…

Sensitivity

Specificity

PPV

NPV

probability that a test detects dz when dz is present... proport…

- true-negative rate... - probability that a test indicates no di…

probability that the person actually has the dz when given a p…

- proportion of negative test results that are TN... - probabilit…

Sensitivity

probability that a test detects dz when dz is present... proport…

Specificity

- true-negative rate... - probability that a test indicates no di…

Normal Distribution (p. 176)

Standard Deviation

Skewness (p. 177)

Null Hypothesis (H0) (p. 177)

1. Bell shaped curve... 2. Gaussian curve... Features:... 1. mean, med…

1 std deviation: 68%... 2 std deviations: 95%... 3 std deviations: 9…

Direction of skewness refers to the direction of the LONGER ta…

states that there is NO difference between groups... Like no dif…

Normal Distribution (p. 176)

1. Bell shaped curve... 2. Gaussian curve... Features:... 1. mean, med…

Standard Deviation

1 std deviation: 68%... 2 std deviations: 95%... 3 std deviations: 9…

Null hypothesis

Case Report or Case series

Case-Control Study

Cohort study

A clinical trial is testing the null hypothesis which states t…

Observations from a single patient or series of patients.

Compares patients who have a disease or outcome to patients wh…

A study group (the cohort) is followed over time and outcomes…

Null hypothesis

A clinical trial is testing the null hypothesis which states t…

Case Report or Case series

Observations from a single patient or series of patients.

Deviation score

nominal data

ordinal data

interval data

D=X-x... Distance a number is from the mean

data are placed in qualitative groups... ex. based on description…

data are placed in ranking orders ... ex. 1st, 2nd, 3rd ... DOESNOT…

data are in a meaningful order

**without**an absolute zero... ofte…Deviation score

D=X-x... Distance a number is from the mean

nominal data

data are placed in qualitative groups... ex. based on description…

cross sectional study

cross sectional study

case control study

case control study

collets data form a group of people to assess frequency of dis…

for disease prevlanece

compares a group of people with disease to a group witout dise…

to calcualte odds ratio

cross sectional study

collets data form a group of people to assess frequency of dis…

cross sectional study

for disease prevlanece

Cross Sectional Study... (observational)

Cross Sectional Study measures

Case Control Study... (observational and r…

Case Control Study measures...

collects data from group of people to assess frequency of dise…

disease prevalence... shows risk factor association with disease,…

compares a group of people with disease to a group without dis…

odds ratio... Ex: patients with COPD have higher odds of a histor…

Cross Sectional Study... (observational)

collects data from group of people to assess frequency of dise…

Cross Sectional Study measures

disease prevalence... shows risk factor association with disease,…

nominal

ordinal

discrete/discontinuous

continuous

qualitative... -gender, zip code, hair color, ethnic group

qualitative... -ordered set of relationships

quantitative... -must be whole integers ... -vital statistics such a…

quantitative... -age, height, weight, serum cholesterol, etc; dat…

nominal

qualitative... -gender, zip code, hair color, ethnic group

ordinal

qualitative... -ordered set of relationships

95% CI

Relative risk/Risk ratio (RR)... Probabil…

Number needed to treat (NNT)

Odds ratio (OR)... Represents that probab…

-When 95% for estimated DIFFERENCE between groups (or within t…

-Probability of an unfavorable event occurring in the tx group…

NNT = 100 / % ARR... MUST ALWAYS around up this number! (e.g. 3.0…

-ratio of two odds, or the ratio of the odds of an event occur…

95% CI

-When 95% for estimated DIFFERENCE between groups (or within t…

Relative risk/Risk ratio (RR)... Probabil…

-Probability of an unfavorable event occurring in the tx group…

case control

increasing sample size will

Cohort Study

Risk difference

subjects enrolled based on disease status, one gorup with dise…

NARROW the confidence interval

subjects enrolled based on EXPOSURE status.

the risk difference between two groups... risk in exposed- risk i…

case control

subjects enrolled based on disease status, one gorup with dise…

increasing sample size will

NARROW the confidence interval