Practice Midterm 1 2.0 - Practice Test Mistakes

Mistake confusing response bias with nonresponse bias

Participation versus answers

Rule for nonresponse bias

People do not respond

Rule for response bias

People respond inaccurately

Why response bias was tempting

People answered the survey

What clue points to nonresponse bias

Many selected people never replied

What clue points to response bias

Answers may not be truthful

Mini example only 40 of 800 people respond

Nonresponse bias

Mini example people lie about exercise habits

Response bias

Memory tip for nonresponse bias

No response

Memory tip for response bias

Wrong response

Concept tested by histogram tail direction

Distribution shape

Rule for determining skewness

Follow the tail

Mistake using the peak to find skewness

Peak does not matter

Why skewed left was tempting

Peak was on the right

Question clue for skewness

Find the longer tail

Mini example tail stretches toward high values

Skewed right

Mini example tail stretches toward low values

Skewed left

Memory tip for skewness

Tail tells the tale

Concept tested by degrees of freedom

Sample formulas

Rule for sample variance denominator

n minus 1

Rule for sample standard deviation denominator

n minus 1

Mistake using n instead of n minus 1

Forgot degrees of freedom

Question clue for n minus 1

Sample

Question clue for n

Population

Mini example sample size 10 denominator

9

Memory tip for sample formulas

Sample subtract one