Biostats 4 and 5

Question 1

why are measures of centrality important

Answer 1

gives us a comparison point to use with a number we have

Question 2

def. mean

Answer 2

sum of all data points/total number of data points

Question 3

def. median

Answer 3

number where half the data points are above and half are below

Question 4

def. mode

Answer 4

number that occurs most often

Question 5

def. range

Answer 5

lowest to highest values

Question 6

def. variance

Answer 6

direct measure of variability in the data - (sum of ((distance between each data point and mean)squared))/N-1

Question 7

def. SD

Answer 7

square root of variance

Question 8

def. interquartile rage

Answer 8

special rage that uses limits corresponding to 25th and 75th percentile

Question 9

def. 95% CI

Answer 9

if you were to go back and sample the pop, then 19/20 times the score would fall within this range

Question 10

CI formula

Answer 10

(mean - 1.96xSD, mean + 1.96xSD)

Question 11

2 general types of research quesitons

Answer 11

1. descriptive

2. hypothesis testing

Question 12

def. DV

Answer 12

the outcome that is being measured

Question 13

def. null hypothesis

Answer 13

that there is no change/diff between groups

Question 14

def. alternative hypotheses

Answer 14

H1 or HA - that there is a difference

Question 15

def. hypothesis testing

Answer 15

use of stats to determine if null can be rejected

Question 16

when to use 2 vs. 1 tailed tests

Answer 16

2 - when we just want to show a difference

1 - when we expect to show a difference

Question 17

def. type 1 error

Answer 17

alpha, usually set at 0.05 - falsely reject null hypothesis

Question 18

def. type 2 error

Answer 18

beta, usally set at 0.2 - falsely accept the null hypothesis

Question 19

def. power

Answer 19

1-B - the probablilty that the analysis will find a difference when a difference actually exists

Question 20

def. p-value

Answer 20

probability that something occured by chance alone