# Summative4.1

rename
ambirnba's
version from
2015-06-04 20:51

## Section 1

Question | Answer |
---|---|

Parametric tests can be applied... | Can only be applied to numerical data w/ normal distribution (can calculate mean & SD) |

Non-parametric tests | Non-normal distribution May not be numerical data, i.e. categorical/nominal data, e.g. ordinal data (exist along a linear scale) |

non-parametric data, comparing 2 groups | mann-whitney U test |

non-parametric data, comparing 2+ groups | kruskal-wallis test |

non-parametric data, comparing rank data | Wilcoxon rak-sum test |

Single blinded | pt doesn’t know if they’re receiving treatment or placebo (to account for placebo effect) |

Double blinded | researcher & pt don’t know if pt is receiving treatment or placebo (to account for researcher’s biases) |

Intention to treat analysis | includes all pts who entered the study, including those who dropped out or weren’t compliant |

per protocol (PP) analysis | includes only those pts who completed the study as originally intended |

which is better: intention to treat or per protocol analysis? why? | PP analysis tends to inflate the benefits & does not account for biases that led pts to be noncompliant, so ITT analysis is better |

## Section 2

Question | Answer |
---|---|

regression is | a mathematical model to describe relationship b/w explanatory (exposure/predictor) variable & dependent (outcome) variable |

linear regression is | a form of regression w/ continuous outcome variable |

correlation coefficient symbol | r |

correlation coefficient ranges between | -1 and 1 |

when does correlation coefficient |r|=1 ? | If exposure variable accounts for all the variation in the outcome variable |

when is r negative? | if outcome decreases w/ increasing exposure |

what is important to keep in mind about correlation? | Correlation ≠ causation |

wilcoxon rank sum test is a ______ test to calculate ___ for ____ samples | Non-parametric test to calculate p for 2 samples (i.e. non-normally distributed data) |

how do you calculate for a wilcoxon rank sum test? | Assigns ranks to data from 2 samples, put data from both samples in order, give them a rank, sum up the ranks of each sample, & then do actual math to calculate p |

cofounder is a | factor associated w/ both the exposure & the outcome |

is cofounding an issue in observational studies? in randomized control trials? | Confounding is especially an issue for observational studies; randomized controlled trials (RCTs) control for possible confounders (but only if they’re correctly identified!) |

you can turn a confounder into a | covariate |

how do deal with confounders? (3 steps) | Must identify confounders, measure their effects on the outcome, & remove that effect in statistical analysis |

## Section 3

Question | Answer |
---|---|

ARR = | RR in placebo group - RR in intervention group |

NNT = | 1/ARR |

NNH (# needed to harm) = | 1/ARI (abs risk increase) |

ARI (absolute risk increase) = | RI in placebo group - RI in intervention group |

hazard: | the rate over time that an event happens (e.g. developing diabetes) |

multi-linear regression model | for continuous outcome, but for 2+ explanatory variables |

logistic regression | for categorical outcome variable (e.g. yes/no for DM dx; dead/alive for Kaplan-Meier curve) |

Proportional hazards models tell you the impact of a risk factor on the | time until an event occurs |

adjusts for people dropping out | (Cox) proportional hazard model |

(Cox) proportional hazards regression assesses a rate | it models the # of new cases (or deaths) per at-risk population per unit time |

(Cox) proportional hazards regression allows you to analyze the effect of ____ on _____ | Allows you to analyze the effect of several risk factors on survival |

________ assesses the cumulative incidence (a measure of disease frequency during a period of time) | logistical regression |

Fixed effect in regression analysis | not relevant outside of this study; something being held constant; those factors aren’t generalizable outside the study |

random (as opposed to fixed effects) | may be generalized outside the study |

## Section 4

Question | Answer |
---|---|

4 principal activities of prevention | immunization, screening, behavioral counseling, & chemoprevention |

Primary prevention: | keeping dz from occurring by removing its causes |

Secondary prevention: | detecting early, asymptomatic dz & treating it to stop it from progressing |

Tertiary prevention: | preventing deterioration/reducing complications after a dz is already present; basically the same as treatment |

Sensitivity: | true positives/total # sick pts; A/(A+C) |

Specificity: | true negatives/total # healthy pts; D/(D+B) |

Positive Predictive Value (PPV): | true positives/test positives; A/(A+B) |

Negative Predictive Value (NPV): | true negatives/test negatives; D/(D+C) |

As prevalence increases, PPV _____ & NPV ___ | PPV increases & NPV decreases |

a method of using mathematical procedures to make intelligent guesses about a population based on a sample & to generate new knowledge | statistical inference |

Statistical significance is defined as | the likelihood that the outcome wasn’t chance (i.e. p<0.05) |

Clinically, “significance” is | importance/relevance |

_______is used for ranked data; correlation coefficient is used for ______ | spearman rank correlation; continuous outcome |

## Section 5

Question | Answer |
---|---|

purpose of Federal Trade Commission (FTC) | meant to protect consumers & prevent anti-competitive or deceptive business practices (e.g. scam cancer tx, dietary supplements, illegal online pharmacies, erectile dysfunction tx, direct-to-consumer genetic tests) |

another name for clinical hypothesis testing | co-selection |

Clinical hypothesis testing = | simultaneously gathering clinical data & searching for illness scripts to generate & test hypotheses |

Clinical reasoning | process by which physicians analyze & organize clinical data to arrive at ddx & write assessment |

Precontemplation | unaware of a problem or no intention to change in the foreseeable future |

Contemplation | ambivalent about changing with no commitment to change in the near future |

Determination/preparation | intends to take action within the next month or has made some recent changes in behavior |

Action | actively attempting to change; generally 1st 6 mo |

Maintenance | has changed and needs to prevent slips and relapse; generally after 6 mo |

adolescents are in formal operational stage | develop capacity for hypothetical thinking |

Propositional thought | ability to reason w/ symbols w/o using concrete representations |

Higher order thinking, incl. metacognition | awareness of mental strategies employed to solve a problem |

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