Variations in Biostat

Question 1

 The tendency of a measurable characteristic to change

o From one individual or setting to another

o Within the same individual or setting at different periods of time

 Statistics is necessary to analyze variability

Answer 1

Phenomenon of Variation

Question 2

 Non-changing: usually applicable to the physical sciences

 Examples: speed of light, π, minutes in an hour

Answer 2

Constants

Question 3

 Measurement or a characteristic

 Values that change within a category

 Values vary from one individual to another or within the same individual at different periods of time

 Examples: Age, gender, height, weight

Answer 3

Variables

Question 4

____________ – the variable under investigation which is hypothesized to have an effect on the outcome ***independent variable – controlled

Answer 4

Independent variable

Question 5

_______________ – the outcome of interest in the study ***it changes depending on something influences it

Answer 5

Dependent variable

Question 6

________________– confounders. Other factors related to both dependent and independent variables ***it is “confounding variable”

Answer 6

Extraneous variables

Question 7

Example

1:  Internet

 Educational networking

 Compliance to Clinical Practice Guidelines

Answer 7

***Answer: independent variable – educational networking Dependent variable –compliance to clinical practice guidelines Extraneous variable – internet

Question 8

Example

2:  Menstrual cycle

 Feminine wash

 Vaginal pH

Answer 8

***Answer: independent variable –feminine wash Dependent variable – vaginal pH Extraneous variable – menstrual cycle

Question 9

Example 3

:  Feminine wash

 Bacterial vaginosis

 Fluconazole

Answer 9

***Answer: independent variable -fluconazole Dependent variable –bacterial vaginosis Extraneous variable – feminine wash OR independent variable –fluconazole + feminine wash Dependent variable – bacterial vaginosis Extraneous variable - none

Question 10

Example

4:

 Stone surgery

 Sambong leaf

 Kidney stones

Answer 10

***Answer: independent variable – stone surgery Dependent variable – kidney stones Extraneous variable – Sambong leaf OR independent variable –stone surgery + Sambong leaf Dependent variable –kidney stones Extraneous variable - none

Question 11

Example 5:

 Biopsy

 Breast CA

 Chemotherapy

Answer 11

***Answer: independent variable -chemotherapy Dependent variable –breast CA Extraneous variable - biopsy

Question 12

Types of Variables

Answer 12

Qualitative vs. Quantitative Variables

Question 13

o Sex, Educational Level, Occupation, Religion, Residence, Disease Status

o Merely labels to distinguish one group from another

o Numerical representation only for coding / labeling and not for comparison

Answer 13

Qualitative

Question 14

____________

o Values indicate a quantity or amount and can be expressed numerically

o Values can be arranged according to magnitude

o Examples: Age, Height, Weight, BP, WBC Count, Hemoglobin level Levels of Measurement

Answer 14

Quantitative

Question 15

Levels of Measurement

Answer 15

1. nominal scale
2. ordinal scale
3. Interval scale
4. ratio scale

Question 16

______________

o Categories used as labels only

o Numbers / Names represent a set of mutually exclusive and exhaustive classes to which individuals or objects may be assigned

o Ex: Sex (M, F) Blood Type (A, B, AB, O) Patient ID, Disease Type ***mutually exclusive, ‘di pwedeng magbago, ikaw lang ang pwedeng magkaroon at ‘di pwedeng magamit ng iba

Answer 16

Nominal Scale

Question 17

____________

o Categories used as labels (like nominal)

o Can be ordered or ranked

o However, the distance between two categories cannot be clearly quantified

o Ex: Psychosocial scales (Strongly agree, agree, disagree, strongly disagree)

o Age Groups (Infant, child, teenager, adult)

Answer 17

Ordinal Scale

Question 18

____________

o Same characteristics as ordinal scales

o Distances between all adjacent classes are equal

o Scales are infinite.

Zero point is arbitrary and does not mean the absence of the characteristic

o Ex: Calendar Time, Temperature, IQ ***zero is arbitrary – merong meaning ang zero -example: Temp- 0 °C (freezing point)

Answer 18

Interval Scale

Question 19

o Same as for ordinal scales with the additional feature that a meaningful zero point exists

o Ex: Weight, Blood Pressure, Height, Number of Teeth ***walang meaning ang zero Ex. # of teeth- 0

Answer 19

Ratio Scale

Question 20

Variable :Age

Measurement Scale:Measured in years

Answer 20

Ratio

Question 21

Variable :Blood Type

Measurement Scale:A, B, AB, or O

Answer 21

Nominal

Question 22

Variable :Asthma severity

Measurement Scale:Mild, Mod, Severity

Answer 22

Ordinal

Question 23

Variable: Diastolic BP

Measurement: Mm Hg by sphygmo

Answer 23

Ratio

Question 24

variable:Weight

Measurekent: Kg using weighing scale

Answer 24

Ratio

Question 25

Variable: Cigarette smoking

Measurement: Cigarette count

Answer 25

Ratio

Question 26

Variable:Live Births

Measurement :Birth rate

Answer 26

Ratio

Question 27

variable: Level of difficulty of a subject

Measurement: Easy, difficult, very difficult

Answer 27

Ordinal

Question 28

Variable: Global efficacy of a treatment

Measurement: Great improvement, moderate improvement, no change, worse

Answer 28

Ordinal

Question 29

variable:Religion

Measurement: Cath, Prot, Muslim, etc.

Answer 29

Nominal

Question 30

Variable: Body Temp Temp in C°

Measurement :by thermometer

Answer 30

Interval

Question 31

Variable: Level of awareness of a WHO guideline

Measurement :Aware, heard about it, not aware

Answer 31

Ordinal