Flashcards
STATS TEST 2
Flashcards do conjunto (33)
- 1Binomial Distribution Meannπ
where π = unknown proportion of 1's occurring - 2BD variancenπ(1-π)
- 3BD Standard Deviation√nπ(1-π)
- 4Binomial ConditionsOutcome must be Binary
"Roll of 4" vs "Roll of not 4"
Success must be constant
Probability of one outcome occurring must not change (ie as a result of another outcome occurring)
TRIALS must be independent therefore. - 5Calculating the probability of x successesFOLLOW the Formula subbing in X, N and π
- 6Binomial distribution is defined by two parameters:Fixed number of trials (n)
&
The constant probability of success on each trial (π) - 775% of NZ children under 18 live with both parents. A random sample of 20 is selected. In the sample, how many children might we expect to find are living with both parents?Find the mean. nπ where n = 20 π = 0.75
= 20 X 0.75
= 15 - 8What is the R code that is used to determine the probability of X successes?dbinom(x=,size=,prob=)
- 9What is the R code used to determine the probabilities of success that are smaller than or equal to a certain value of Xpbinom(q=,size=,prob=)
- 10How do you determine the probabilities of success that are greater than or equal to a certain value of XWork out the success of each probability and them together. OR use
pbinom(q=,size=,prob=,lower.tail=FALSE) - 11Reference Ranges Contain:The central 95% of all the values of the measures in a healthy population.
- 12Pnorm gives you the area:Below or above a certain point Q
- 13Qnorm will give you:the value of the normal distribution defined with a particular mean and sd above or below an area where p occurs
- 14Lower Limit of Normal for Reference Ranges is calculated by:µx - qnorm(standard deviation)
- 15Upper limit of the normal for a reference range is calculated by:µx + qnorm(standard deviation)
- 16The shape of the log - Normal distribution depends on __ and is always ___ skewedthe standard deviation, positively
- 17The sampling distribution of the mean is___, and follows a ___ it is denoted bythe distribution of a means, from many samples, Normal Distribution, X Bar
- 18The Central Limit Theorem States:That given a significantly large sample size with a particular mean and variance, the mean of samples taken from the population will be approximately equal to the mean of that population.
- 19The mean of the sampling distribution is = The standard deviation of the sampling distribution is =µx & SigmaX
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√N - 20The standard deviation of the sampling distribution is also known as: and it is a measure of:The standard error of the mean, the precision with which we have estimated the mean.
- 21The larger the sample size the smaller the ____Standard Error (More compact distribution, greater precision)
- 22If X is normal than then the sampling distribution of the means is:normal for any n
- 23If X is not normal, X bar is:Approximately normal for large sample sizes
- 24Confidence intervals are calculated using:The distribution of the sample means = X Bar
- 25The alpha value denotes:a specific amount of tail probability given the range of the confidence interval
- 26The multiplier used to calculate a confidence interval is:The critical value calculated using qnorm(alpha value/2,mean=,sd=,lower.tail =TRUE/FALSE)
- 27The t distribution is ____, and gives larger ___ reflecting a ___A family of curves that has a specific degree of freedom in relation to the size of the sample, critical values, wider and less precise confidence interval.
- 28The T distribution is used whenthe distribution of X is normal, and when the sample size is sufficiently large.
- 29The T multiplier is found by the code:qt(p,df) where p = a specific probability and df= degrees of freedom
the probability will be the tail areas we are excluding therefore 1-alpha value/2 - 30For intervals using 1 single sample mean the degrees of freedom will be equal to:v = n - 1
- 31A 99% confidence interval is wider than the 95% confidence interval because :That is the price we pay to be more sure that the interval contains the true mean
- 32If the sample size is smaller the interval will beWider, it is less precise due to the lack of data
- 33When sample size calculations:The standard multiplier is used (1.96 for 95% CI)
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- FlashCards sobre STATS TEST 2, criado por Bex Chrystall em 01-09-2017.
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- Bex Chrystall
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