Chapter 7.2 Flashcards
What is the relationship between proportion and percent?
Proportion is percent in decimal form
Proportion of people in a category=# of people in the category/total # of people
pg. 426
What is the equations for standard deviation for proportion?
@=`/pq/n
sigma=square root of p times q divided by n
pg. 427
How to find the exact middle range?
Main equation:p+or-Zsub(a/2)X`/pq/n
breakdown: a=1-confidence
a/2
invNorm(a/2,0,1,right)=Zsub(a/2)
same equation for the confidence interval
pg. 429 & 430
What is the confidence interval?
The amount of certainty that the actual pop proportion will be in the range predicted
equation: phat+or-Zsub(a/2)X`/phatqhat/n
or phat+or-the margin of error
pg. 432
What is the symbol for the sample of a proportion?
P
called p hat
the ^(hat) is only used for samples not for population
pg. 433
What is the margin of error?
The amount the predicted range might be off from the true population
Equation: E=Zsub(a/2)`/phatqhat/n
When n gets bigger, then E gets smaller; so a larger sample results in a smaller margin of error
pg. 433
When is a confidence interval consistent with a claim?
If a claim falls within the confidence interval then the sample is consistent with the claim, if it falls outside the range then it’s not cosistent
pg. 436
When does a confidence interval contradict a claim?
-contradict is the opposite of being consistent
If the claim falls outside the confidence interval, then the sample result contradicts the claim, if it falls within then it doesn’t conradict the claim
pg. 438
What if the claim is that the population parameter is more than some value?
if the value falls within the confidence interval then te results don not support the claim, if the entire confidence is above the value then the results support the claim that the pop is more than the value
pg. 439
What is the equation to determine the minimum sample size?
When an estimate of the sample proportion (p hat) is known: n=[Zsub(a/2)]^2phatqhat/E^2
When an estimate of the sample proportion (p hat) is NOT known: n=[Zsub(a/2)]^2X.25/E^2
n=[Zsub(a/2)]squared times p hat times q hat divided by E squared
-When finding the minimum sample size always round UP to the next whole number
pg. 442
Useing the calculator to find the confidence interval
1)Stat
2)Over to Test
3)Down to 1-PropZint(alpha A)
4)Enter x=the number of successes(must be a whole #) and n=the number of sample values
pg. 435
How to you find P hat?
Pn=p hat
e.g. a survery of 1007 adults find 85% answer yes
-85% of 1007 is 855.95 (can’t have .95 of a person) so it must be 856 people so it would be 856/1007=.85005 so .85005 is p hat
pg. 434
