STATISTICS

Descrição

Quiz sobre STATISTICS, criado por raquel galindo em 21-06-2016.
raquel galindo
Quiz por raquel galindo, atualizado more than 1 year ago
raquel galindo
Criado por raquel galindo quase 8 anos atrás
8
0

Resumo de Recurso

Questão 1

Questão
S_x ̅ =s⁄√n is an estimate of:
Responda
  • the standard deviation of the sampling distribution of the mean
  • the standard error of the mean
  • o_x ̅ =o⁄√n
  • all of the above

Questão 2

Questão
The 68-95-99.7 rule indicates that for a normal distribution N(,o):
Responda
  • 68% of the observations fall within 1 o of the mean 
  • 95% of the observations fall within 1 o of the mean 
  • 99.7% of the observations fall within 1 o of the mean 
  • none of the above

Questão 3

Questão
The Law of the large numbers implies that
Responda
  • As the simple size increases  will change being closer to x ̅
  • As the simple size increases the difference between the parameter and the statistic will increase
  • As the simple size increases the simple proportion p ̂ will be closer to the population proportion p
  • All of the above

Questão 4

Questão
When estimating the populational mean, as we increase the simple size
Responda
  • The simple distribution becomes more concentrated (less disperse)
  • The standard error decreases
  • The accuracy of the inference increases
  • All of the above

Questão 5

Questão
Suppose we toss a fair coin 100 times. Knowing the true population of heads is 0,5 find out the 2 decimal approximation of the probability that the sample proportion of heads is between 0.4 and 0.6:
Responda
  • 0.05
  • 0.95
  • 0.5
  • none of the above

Questão 6

Questão
for a fixed simple size and standard error a confidence interval with a 99% confidence level is:
Responda
  • wider than a 95% confidence level interval
  • narrower than a 95% confidence level interval
  • of the same width than a 95% confidence level interval
  • wider or narrower depending on the standardized statistic (in relation to the parameter that is estimated)

Questão 7

Questão
the F statistic in an ANOVA used to test an average differences always increases when:
Responda
  • the within group variability increases
  • the between group variability increases
  • the total variability increases
  • all of the above

Questão 8

Questão
We are willing to conduct a paired-samples two tailed test on the difference between the populational means of x and y. The simple mean of x is 9 and the sample mean of y is 10; the simple size is 40. The variance of the difference in sample values is s_d^2=16. What is the conclusion of our test?
Responda
  • We reject the null hypothesis, the populational means are significantly different
  • We fail to reject the null hypothesis, the populational means are not significantly different
  • We accept the null hypothesis, the populational means are the same
  • We reject the null hypothesis, the populational means are not significantly different

Questão 9

Questão
When the correlation coefficient between two variables x and y is larger
Responda
  • The estimate for the slope of the regression line has a larger value (even when the slope is negative)
  • The determination coefficient is also larger (even when the correlation is negative)
  • The determination coefficient is smaller (even when the correlation is positive)
  • None of the above

Questão 10

Questão
If we find the following confidence interval for the slope of a regression β∁ (-0.5,1.5) at a 95% confidence level:
Responda
  • The simple slope β ̂ is 0.5
  • There is no significant linear association between x and y at a 5% significance level
  • The simple correlation coefficient r is positive
  • All of the above

Questão 11

Questão
When the determination coefficient equal 1:
Responda
  • There’s a perfect linear association between x and y
  • When y increases x increases
  • When y increases x decreases
  • None of the above

Questão 12

Questão
Knowing that for a linear regression model Σ(
Responda
  • 2
  • 10
  • 8
  • 18

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