stats Flashcards
what is the explanatory variable
the independent variable - x axis - change easily
what is the response variable
y axis - something we measure
when is a binomial distribution/approx valid in normal distribution
- number of trials (n) must be large
-probability of success (p) must be close to 0.5
what must a binomial distribution have
- a fixed number of trials
-two possible outcomes
-trials are independent
-fixed probability of success
what does discrete uniform probability mean
all probability is the same
when do we fail to reject h0 (CRITICAL REGION/VALUE)
not in the boundary
when do we reject h0 (CRITICAL REGION/VALUE)
in the boundary
what is a census and its adv and disadv
- measures every member of the population
adv - more accurate
disadv - wastes lots of time and money
what is a sample and its adv and disadv
- a selection of a subset of the population
adv- less data to process
disadv- may not be as accurate
what is simple random sampling
every sample has equal chance of being selected
what is systematic sampling
the required elements are chosen at regular intervals from an ordered list - the starting point is chosen randomly
what is stratified sampling
used to select a sample that is representative of different groups
what is the equation for stratified sampling
number sampled = (num in stratum/num in pop) x 100
what is quota sampling
selects a sample that reflects the characteristics if the whole pop
what is opportunity sampling
taking the sample only from items or people available at the time of the study and who fit the criteria being looked for
is simple random sampling random or non random
random
is systematic sampling random or non random
random
is stratified sampling random or non random
random
is quota sampling random or non random
non random
is opportunity sampling random or non random
non random
what data is qualative
letters
what data is quantative
numbers
discrete - specific amount - eg shoe size
continuous - can go to any decimal - eg length
is the median affected by extreme values and outliers
no
what is the mean affected by
extreme values and outliers
what do i input in the calculator as the x value in a frequency table
the midpoint
do we ignore the add and subtract in coding the standard deviation
yes
equations for histograms
- area = class width x fd
- f = k x fd
- fd = f / cw
-area = kf
