27 Inferential Stats Flashcards
useful for descriptive, predictive, causal research; draw generalizations from inferences from sample stats to pop. parameters
inferential stats
why infernces probabilistic?
even with random sampling, always chance sampling error
what are sample stats?
estimates of actual pop. parmeters
Sx=
s/sq rt of n (sample standard error)
use t distr for:
confidence interval when n is small (<30)
what is central limit theorem?
as n becomes large, distr of sample means approaches normal distr
number of scores free to vary when calc stat
df
use of z or t distr?
estimate prob of drawing certain sample mean from pop., calc. confidence intervals
to look up t values, need to consider:
direction, probability, degrees of freedom
what is lvl of significance?
calc probability that what seen in sample data is generalizable to pop.
process of deciding statistically if findings due to chance or real effect, at certain lvl of probability
hypothesis testing
steps in hypo test?
1) state alt hypothesis (prediction for evaluation) 2) state null hypothesis
why is directional Ha advantage?
^ prob reject Ho
if obt > crit, ___ Ho
reject
if obt < crit, ___ Ho
retain
