Lecture 2 Flashcards
what are statistically methods useful for
studying, analyzing, and learning about populations of experimental units
define experimental or observational unit
an object about which we collect data
person, thing, event, tree
thing we measure
define population
set of all units - all possible measurements we could take
set of all unit that we want top study
can be infinite
define variable
what we observe
characteristic or property of an individual experimental or observational unit in population
like age, weight, counts
define experiment
measure outcome of some physical action we take
define sample
a subset of units in population
Collection of observations we make
represents pop
describe random sample
assume some things about how data was collected
define statistical inference
estimate, prediction or some generalization about population based on info contained in sample
does evidence in data support physical law
Characteristic
describe sample mean
sample mean = sum of observations/# of obs
describe measure of reliability
statement
usually quantitive
about a degree of uncertainty associated with a statistical inference = using limited number of obs= wont learn everything
based on data of sample
give examples of measure of reliability
flipping coin = heads all 3 times= chance of heads is 1
but experiment limited
based on data of sample = size mainly
how many things do we need to determine in study
7 things
name all 7 things we need to determine in study
1 - Objectives of study
2 - experimental units
3 - population under study
4 - characteristic(s) of interest
5 - sample
6 - inference(s) of interest
7 - measure(s) of reliability
describe objectives of study - determine in study
what questions we want to answer in study
important for ethics approval if using humans
describe experimental units - determine in study
people
machines
transactions
what we could possibly measure
describe population under study - determine in study
set of experimental units
(all first year undergrads, all transactions at Walmart in a day)
describe characteristic of interest - determine in study
variable(s) measured on th experimental unit
can measure multiple but mainly we focus on one
describe sample - determine in study
subset of pop under study
if we could = take census (whole population) but if cannot= take sample
describe inferences of interest- determine in study
about pop based on sample
describe measure of reliability- determine in study
to account for limited sample
describe infinite vs finite pop
if finite = sample = all the obs units = population = census
but infinite = # of possible experimental units we could get is infinitely large
describe sub cutaneous fat necrosis in newborns - generally
Some newborns suffer asphyxia during birth
A treatment for perinatal asphyxia is called therapeutic hypothermia= involves lowering the child’s body temperature for 72 hours, then the child’s body temperature is slowly raised to normal
Some children develop the rare condition sub-Cutaneous fat necrosis (SCFN)= this usually disappears within a few weeks but some children develop more serious complications
describe sub cutaneous fat necrosis in newborns - population
all full term newborns who may suffer from perinatal asphyxia that will get hypothermia as treatment (units of interest)
describe sub cutaneous fat necrosis in newborns - variable of interest
if child developed scfn (yes/no)
birthweight (sample mean)
other risk factors
could measure all or specific one