exam 2

examples of several forms of bias

a non-representative sample; an experiment that is not blinded; a researcher with personal stake in the outcome distorts the true meaning of data

what is a placebo

a placebo lacks the active ingredient of a treatment being tested in a study, but is identical in appearance to the treatment

what is bias? How can it affect a statistical study?

bias refers to any problem in the design or conduct of a statistical study that tends to favor certain results

expected value of a random variable

given a random variable with different values, each with their own probability, the expected value of the random variable is like a weighted average of the values and their respective probabilities

how can making an experiment single-blind or double-blind help

if an experiment is blinded, then any effect arising from psychological factors should affect all groups equally

why is it so important that a statistical study use a representative sample?

if the sample fairly represents the population as a whole, then it is reasonable to make inferences from the sample to the population

what is the distinction between qualitative data and quantitative data? give a few examples of each

qualitative data describes categories, while quantitative data represents counts or measures. brand names of shoes in a consumer survey and eye color are examples of qualitative data. heights of students and quiz scores are examples of quantitative data

briefly describe four common sampling methods.

simple random sampling, systematic sampling, convenience sampling, stratified sampling

describe the placebo affect and how it can make experiments difficult to interpret

the placebo effect refers to a situation in which a patient improves simply because they believe they are receiving a useful treatment. it can sometimes be difficult or impossible to distinguish between effects that arise from the actual treatment and those that arise from psychological factors