DESCRIPTIVE BIOSTATISTICS

Question 1

name this category of statistic?

organize, summarize and communicate data

• measures of central tendency
• measures of dispersion

Answer 1

descriptive statistics

Question 2

name this category of statistic?

generalize findings from sample to a larger population

• estimation of parameters
• hypothesis testing

Answer 2

inferential statistics

Question 3

what is this type of variable?

data can take on any value within a set range
i.e temperature, height, weight

Answer 3

continuous variable

Question 4

what is this type of variable?

data can only be one of a limited set of values

• usually whole numbers
• count data
  i. e number of children, number of students in class

Answer 4

discrete variable

Question 5

what is this type of variable?

named categories

• no implied order among categories
• qualitative
  i. e gender, blood types

Answer 5

nominal (categorial) variable

Question 6

what is this type of variable?

nominal variables with only two categories
i.e yes/no, male/female

Answer 6

dichotomous variable

Question 7

what is this type of variable?

set of categories arranged in a meaningful order

• differences between categories cannot be considered equal
• qualitative
  i. e stage of cancer, pain levels

Answer 7

ordinal (ranked) variable

Question 8

what is this type of variable?

ordered data with equal distances between values

• zero point isn’t meaningful
• quantitative
  i. e IQ scores, temperature

Answer 8

interval variable

Question 9

what is this type of variable?

data with equal intervals and a meaningful zero point

• quantitative
  i. e height, weight

Answer 9

ratio variable

Question 10

what is this type of variable?

variable being manipulated by the investigator

• intervention of interest
• not affected by the other variables being measured
• also called the predictor variable
  i. e dose

Answer 10

independent variable

Question 11

what is this type of variable?

variable being measured to determine the outcome

• changes as a result of intervention
• also called the outcome variable
  i. e blood pressure

Answer 11

dependent variable

Question 12

what is this measure of central tendency?

arithmetic average of a data set

Answer 12

mean

Question 13

what is this measure of central tendency?

middle value of a data set

Answer 13

median

Question 14

what is this measure of central tendency?

value which occurs most frequently in a data set

Answer 14

mode

Question 15

what is this measure of dispersion?

difference between the highest and lowest values in a data set

Answer 15

range

Question 16

what is this measure of dispersion?

difference between the 1st quartile and 3rd quartile of a data set

Answer 16

interquartile range

Question 17

what is this measure of dispersion?

average of the squared difference of the means

Answer 17

variance

Question 18

what is this measure of dispersion?

square root of the variance

Answer 18

standard deviation

Question 19

what is this common distribution?

Symmetric
Bell-shaped with single peak
Continuous variables
Mean = median = mode
Empirical Rule:
-68% of all observations fall within 1 standard deviation of the mean
-95% of all observations fall within 2 standard deviations of the mean
-99.7% of all observations fall within 3 standard deviations of the mean

Answer 19

normal distribution

Question 20

what is this common distribution?

Discrete random variables
Fixed number of independent yet identical trials
-Every trial ends in success or failure
-Variable of interest is number of trials that ended in a success
Approaches a normal distributions with large sample size

Answer 20

binomial distribution

Question 21

what is this common distribution?

asymmetric bell-shaped curve
positive/negative skewed distribution

Answer 21

skewed distribution

Question 22

Skewed to the right

Mean > median

Answer 22

positive skewed distribution

Question 23

Skewed to the left

Mean < median

Answer 23

negative skewed distribution