gyu other questions you messed up chapter 1 - 3 Flashcards
stratified random sampling
when important groups within a population are separately sampled
those samples are combined to form a full sample
what is a nominative variable?
a qualitative variable with no meaningful ordering
what is undercoverage?
occurs when some population elements are excluded from the process of selecting the sample
It results in being unbalanced
what is nonresponse
occurs whenever some of the individuals who were supposed to be included don’t want to come or simply can’t
what is the science of using a sample of measurements to make generalizations about the important aspects of a population of measurements?
statistical inference
If we examine all of the population measurements, we say that we are conducting a:
census of the population
what is a strata
In order to select a stratified random sample, we divide the population into nonoverlap-ping groups of similar elements (people, objects, etc.)
these groups are strata
what is systematic sampling
an alternative to random sampling
In order to systematically select a sample of n elements without replacement from a frame of N elements, we divide N by n and round the result down to the nearest whole number
Calling the rounded result ℓ, we then randomly select one element from the first ℓ elements in the frame—this is the first element in the systematic sample
The remaining elements in the sample are obtained by selecting every ℓth element following the first (randomly selected) element
what are the flaws of multiple choice survey questions?
may fail to discover the reasons underlying a respondent’s choice of a particular answer
what are the flaws of dichotomous survey questions?
possible responses are quite limited
what are the flaws of open-ended survey questions?
can be difficult to evaluate and summarize
what is a ratio variable
a quantitative variable measured on a scale such that ratios of its values are meaningful and there is an inherently defined zero value
variables such as salary, height, weight, time, and distance are ratio variables
what is an interval variable
quantitative variable where ratios of its values are not meaningful and there is not an inherently defined zero value
Temperature (on the Fahrenheit scale) is an interval variable
what does a frequency distribution do
summarizes the number of items in each number of several non overlapping classes
what does a frequency polygon do
useful for comparing several distributions
what is the cumulative relative frequency
when all the relative frequencies equal to 1.00
how do you construct a frequency polygon
you plot points above each class’ midpoint at a height equal to the relative frequency of a class
how do you calculate the number of classes in a frequency distribution
2^k > n
k is the number of classes
what type of chart can:
identify quality problems
suggest where a process needs improvement
help prioritize problem solving activities
a Pareto chart
when would you use the Chebysev theorem?
when the curve is not mound shaped (for ex: two peaks)+
also not much skewness
the population has mean and standard deviation
for the chebysev theorem, why would you not use a mound shape for it
because you can use the Empirical rule
what does the Chebysev theorem tell you?
how many standard deviations the x is from the mean and shit
same as empirical rule, but with more fucked up shid
what does the Chebysev theorem tell you?
how many standard deviations the x is from the mean and shit
how much of the population lies between a certain amount if standard deviations
same as empirical rule, but with more fucked up shid
why would it not be okay to use any formula using standard deviation for a population with a lot of skewdness
the standard deviation will be inflated as shied
