BIOL 437 Week Three

Question 1

study design

Answer 1

• program that directs the researcher along the path of systematically collecting, analyzing and intrepreting data
• allows for descriptive assessment of events and for statistical inference

Question 2

study types

Answer 2

-experimental
-observational
>descriptive
>analytic

Question 3

descriptive epidemiology

Answer 3

• examining the distribution of disease in a population
• observing the basic features of it’s distribution
• when, where, who

Question 4

analytic epidemiology

Answer 4

• testing a hypothesis about the cause of disease by studying how exposures relate to the disease
• observational or experimental

Question 5

analytic epi-studies require info to

Answer 5

• know where to look
• know what to control for
• develop viable hypotheses

Question 6

analytic epi- is built around

Answer 6

-the analysis of the relationship between two items
>exposures
>effects (disease)
-looking for determinants or possibe causes of disease
-useful for hypthesis testing

Question 7

descriptive statistics

Answer 7

-can take on various forms
>tables
>graphs
>numerical summary measures
-application of statistical methods makes it possible to effectively describe the public health problem

Question 8

helpfulness of descriptive epidemiology

Answer 8

• info about a disease
• clues to identify a new disease
• identifies the extent of the public health problem
• obtains a description of the problem that can be easily communicated
• identifies the population at greatest risk
• assists in planning and resource allocation
• identifies avenues for future research

Question 9

4 types of descriptive studies

Answer 9

1. Ecologic studies: population level
2. Case reports
3. Case series
4. Cross-sectional surveys

Question 10

ecological study

Answer 10

-involves aggregated data on the population level
-ecological fallacy
>when population level are used for individual level
-advantage: annoymous
-disadvantage: can’t have individual correlation

Question 11

case report

Answer 11

-involves a profile of a single individual

Question 12

case series

Answer 12

-involves a small group of patients with a similar diagnosis
-provide evidence for longer scale studies
>hypotheis gathering

Question 13

cross-sectional survey

Answer 13

• prevelance survey
• short period of time
• no follow-up
• all variables measured at a point in time
• no distinction between potential risk factors and outcomes
• good for examining associations between factors

Question 14

strengths of cross-sectional

Answer 14

• several associations at once
• relatively inexpensive
• short period of time
• control
• biases due to observation and loss to follow up does not exist

Question 15

weakness of cross-sectional

Answer 15

-unable to establish sequence of events
>association NOT causation
-influenced by response bias
-no follow-up
-no incidence or relative risk data

Question 16

serial surveys

Answer 16

-cross-sectional surveys that are routinely conducted

>regular frequencies

Question 17

cohort study

Answer 17

-of persons who have been exposed and are followed over time with selected health outcomes

Question 18

case-control study

Answer 18

-of persons who have been exposed and are followed over time with selected health outcomes

Question 19

case-control study

Answer 19

• grouping people as cases and controls

- are cases more/less likely than contorls to have had exposures/behaviours

Question 20

2 methods for age-adjusted rates

Answer 20

1. Direct

2. Indirect

Question 21

direct method

Answer 21

-assume males and females have same rate

Question 22

indirect method

Answer 22

-age-specific rates are unstable
-standardized morbididty ratio (SMR)
>know total counts
>use rate from other gender

Question 23

SMR=1

Answer 23

-events observed were same as expected

Question 24

SMR>1

Answer 24

-more events observed than expected

Question 25

SMR<1

Answer 25

-fewer events observed than expected

Question 26

4 types of data

Answer 26

1. Nominal 2. Ordinal 3. Discrete 4. Continuous

Question 27

nominal

Answer 27

- categorical: unordered - dichotomous: 2 levels - multichotomous: more than 2 levels

Question 28

ordinal

Answer 28

-categorical: ordered, scale data

Question 29

discrete

Answer 29

-quantitative -differ by fixed amounts Ex. number of sick kids

Question 30

continous

Answer 30

-quantitative -values on a continuum -interval and ratio Ex. age, weight

Question 31

interval

Answer 31

- units of equal magnitude without an absolute 0 | - ex. temperature

Question 32

ratio

Answer 32

-units of equal magnitude, absolute 0 >starting point is 0 Ex. HR, BP, distance

Question 33

attack rate

Answer 33

- cumulative incidence rate | - diseases or events that affect a larger proportion of the population than the conventional incidence rate

Question 34

measures of central tendency

Answer 34

- mean - median - mode

Question 35

measures of depression

Answer 35

- range - interquartile range - variance - SD - coefficient of variation

Question 36

frequency distributions

Answer 36

- values of a variable and records with each value | - rapid visual assessment

Question 37

spread

Answer 37

- variation of dispersion - distribution from a central value ex. range and SD

Question 38

shape

Answer 38

- symmetrical vs. assymmetrical/skewed | - "tail" of the distribution-skewed

Question 39

positively skewed

Answer 39

- tail to right | - central location is to the left

Question 40

negatively skewed

Answer 40

- tail to left | - central location to right

Question 41

mode

Answer 41

- value that occurs most in data - could have more than one - used for 'descriptive' measure

Question 42

median

Answer 42

- middle value of data set in rank order - 50th percentile of the distribution - descriptive

Question 43

arithmetic mean

Answer 43

-value closest to all the other values in a distribution -often used in statisical analyses -best descriptive measure for normally distributed data >not great for skewed data

Question 44

geometric mean

Answer 44

-mean of data on a log scale >normally distributed -ex. serial dilutions or environmental sampling

Question 45

standard deviation

Answer 45

- measure of spread - often used with the arithmetic mean - 'variability in a data set'

Question 46

standard error (SE) of the mean

Answer 46

- variability expected of repeated samples from the same population - quantifies variation in sample means * used to determine confidence intervals