When we have our next class (probably Friday) we will get back into chapter 18, sampling distributions!
- Much of this math will be based on the Normal model--so it's a great idea to review your chapter 6 notes about z scores, normalcdf, and invnorm!
- 2 of these 6 homework MC are based on this chapter 6 stuff!
- And if you'd like to get a head start, here is the weekend homework! I may add more to this...we'll see what happens in class....
- Page 428:
- Check the conditions: 7b, 11, 23 (conditions only!)
- Normal Model Review: 25ab
- Also do #1abd
- For a,b...think! You got this!
- For 1d we're asked why we can't use a Normal model here--that's because one of the 3 conditions for a sampling distribution for proportions fails....to answer 1d, state/show which of the 3 conditions fails
- You can also read chapter 18! The more you read on your own, the more "ahead" you'll be!
- Finally, here are some writing templates on the conditions if you're trying to start your homework:
- Randomization: we can only know if a sample is random if this information is given to us in the context! If not, we'll have to assume we have a random sample or random assignment or representative data. Try to use one of the sentences below...
- "It is stated that our sample of _____ was collected randomly."
- "It is stated that our sample of _____ is a representative sample."
- Or, look for random assignment...
- If neither of those apply....
- "We can assume our sample of _____ is a random/representative sample."
- 10% Condition: here we have to check that our sample (size) is less than 10% of the population size! We might not know the size of the population, so we might also have to "assume" for this condition
- "Our sample of ______ is less than 10% of all _____ (define the population, in context)."
- "We can assume that our sample of ______ is less than 10% of all ______."
- Remember, the third condition differs depending on the type of data...
- Quantitative Data = means = sampling distribution for means (23)
- Large Enough Sample:
- "Our sample of _______ is large enough." (We want a sample of at least 25)
- OR...
- "It stated that the distribution of _____ is unimodal and symmetric (approximately Normal)."
- Categorical data = %'s = proportions = sampling distribution for proportions (7b and 11)
- Success/Failure Condition:
- np > 10
- nq > 10
- Do the math!
- p represents the % that we are given in the question
- q = 1 - p; so if p = 70% or 0.7, then q = 1 - 0.7 = 0.3
- And remember, n is our sample size
And here are those MC for tonight's (Wednesday's) HW:
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