lecture 1 pt 1
what is categorical (qualitative) date
classifies observations into named categories
regular categorical: categories denoted by a word -/
+
ordinal categories: can be put into a rank (stages of cancer)
explain simple random sampling, stratifies sampling , and clustered sampling
simple random: randomly select cases from the population w/ no implied connections
Stratified sampling: strata (subgroups) then random selection from each subgroup
cluster sampling: segregation then you only sample that one homogeneous cluster
what is the placebo effect
experimental units showing improvement simply because they think they are receiving the real drug
what are the 4 different types of modality
unimodal = one peak
bimodal= 2 peaks
multimodal = multiple peaks
uniform = box
how do you read a box plot
how far can whiskers extend
;)
they can extend 1.5X IQR away
what is numerical (quantitative) data
observations are represented by true numerical values
continuous date - observations represented using complex numbers within a given range (weight)
discrete date - observations are represented by whole numbers (# of kids)
the difference between prospective study and retrospective studies
prospective : collects info as events unfold
retrospective: collecting data on events that have already taken place
explain blinding
when the experimental units do not know if they are the control or treatment group
what are the 3 different types of skewness
right skew = skinny on right
left skew = skinny on left
symmetric
what would mean and median look like in a right/left skewed chart
right skewed: mean> median
left skewed: mean<median
the difference between positive and negative association
positive: 1 goes up they all go up
negative: 1 goes up the others go down
what are explanatory variables
factors
conditions we can impose on the experimental units to determine their effects
what is double blinding
when no one knows who is the control and treatment group
median
middle number
if you have 2 of them, add them then divide by 2
null hypothesis
what you thought
what is the difference between a population and a sample
population: all possible members of a specific group
sample: only a subset of all possible members of a specified group of interest
what are blocking variables
characteristics that the experimental units come up with that we would like to control
do you know what a scatterplot and a dot plot look like
go look it up if you don't
how do you define quartiles
25th percentile -q1
50th percentile q2
75th percentile q3
middle 50% = IQR
alternative hypothesis
what are the 3 different types of sampling biases and explain what they intel
non-response : a small response from the people can not be representative
voluntary response : people who volunteer to respond because they have a strong opinion
convenience sample: people who are more accessible
another name for placebo
fake
control group
how do you calculate mean
add everything then / by the amount of individual numbers
what is IQR
q3-q1
who's going to get at least a 3.5 gpa this semester
WE ARE !!!!!!!!!!!