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Epidemiology & Biostatistics Test 4 questions and answers graded A+ 2024/2025
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Epidemiology & Biostatistics Test 4 questions and answers graded A+ 2024/2025
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Epidemiology & Biostatistics Test 4Hypothesis:
or more population manner are similar to each other
no distinction - ANSnull hypothesis
speculation:
no longer all of the populace manner are the identical - ANSalternative speculation
number one inferential statistic of interest is - ANSthe dating / distinction between or extra
unknown populace way
- evaluate two approach from two unbiased populations (impartial pattern comparisons)
- compare two approach from the identical population (associated samples comparisons)
- the null is still the identical regardless of if it's miles between two independent or the equal
populations
Inferences from Two Independent Populations:
Want to examine approach between exactly ___ samples drawn ____ ______ from two
independent populations (ex: drug vs. Placebo businesses in RCT drug trial) - ANS2
at random
For independent populations - ANS- samples MUST be randomly decided on
- samples should come from populations which might be observationally impartial of each
different
If conditions are met (samples drawn at random and samples got here from the populations
observationally independent of each different) we can proceed with suitable inferential
evaluation primarily based on: - ANS- whether or not pattern sizes are same
- whether sample variances are same
What is the very best/maximum simple inference - ANSequal pattern sizes / same variance
Equal sample sizes/identical variance
speculation:
populace imply 1 = populace imply 2
(two population manner are the equal) - ANSnull speculation
Equal sample sizes/equal variance
hypothesis:
population imply 1 does NOT identical populace mean 2
(2-tailed take a look at) - ANSalternative hypothesis
,Equal pattern sizes/equal variance
hypothesis:
population mean 1 < or > population mean 2
(1-tailed test) - ANSalternative hypothesis
a statistical exam of two population way - ANSt-take a look at
T fee results in the - ANSp-cost
the p price is based totally on the value of the - ANSt statistic
very massive values of T information cause: - ANSrejection of the null speculation
In order for T to be big, the numerator must be very ______. - ANSBIG
which might imply that the distinction between the two approach may be very large
Larger the T price... - ANSthe bigger the distinction there is among the 2 pattern way
the smaller the P cost results in - ANSrejecting the null hypothesis
P values of the check estimates possibility that the _______ speculation is real given the pattern
consequences - ANSnull
P-values < 0.05 generally lead to ______________ of the null
(95% confidence level) - ANSrejection
If you reject the null, the conclusion would be - ANSthe two population means, as estimated by
their respective sample means, are NOT the same as each other
The _____________ could also be utilized as well, if such are reported/available to determine
acceptance/rejection of null - ANSconfidence interval approach
Estimated 95% confidence intervals that don't include 0 lead to a ________ of the null -
ANSrejection
- it would lead to rejection because in order for it to be zero, the two values of the sample mean
would be the same. If the two values are NOT the same, the value would NOT be zero
If there is no "zero" in the confidence interval you can conclude - ANSthat the two groups are
different and reject the null
, if you have unequal sample sizes / equal variance, the hypothesis testing procedure is -
ANSidentical to equal sample tests
95% confidence interval also identical to equal samples except that SE estimate will differ
somewhat
What is the consequences of unequal variance on hypothesis testing for sample means -
ANSincrease risk of Type I and/or Type II errors
if sample sizes are roughly equal... - ANSequal variance assumption may be reasonably
employed
if sample sizes are significantly unequal.... - ANSmore complex statistical routines must be
employed to account for heterogeneity of variance
If the sample sizes are roughly equal to each other, you can assume - ANSequal variance
unequal variance is more common in - ANSgroups that are widely different from each other
(ex: one group is 2 times the size of the other, etc.)
assumption of sample independence is NOT valid in what cases - ANScases of inferences from
Two Related Populations
If you are using inferences from two related populations, what T-Test will you have to use -
ANSPaired T-Test
______ is used to test hypothesis for differences between non-independent sample means -
ANSpaired t-test
hypothesis testing and confidence interval estimation for non-independent samples is
____________ as with independent samples test - ANSexactly the same
where to differences lie for hypothesis testing and confidence interval estimation for
non-independent samples and independent samples test - ANSdifferences lie in the
interpretation of results
(interpretation is used to compare the sample population)
inferences from more than two populations
- if you have 4 different sample/group means estimated what inferential test would you use? -
ANS- could conduct 6 different independent group mean comparisons for each of the possible
combinations
- ANOVA
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