STA1010 Statistical Methods for Science Flashcards
What is the meaning of the term “expected value” for a random variable?
The long-run average value
A poll is planned to determine what proportion of all students favor an increase in fees to support a new track and field stadium. The questionnaire will be published in the student newspaper and the first 1000 completed questionnaires will be analyzed.
What is the main problem with this study design?
Volunteer sampling
For any two events A and B, the probability of event A and B occurring together, P(A and B), will always be given by
P(A).P(B|A)
Determine whether the given study is an observational study or an experiment.
A doctor performs several diagnostic tests to determine the reason for a patient’s illness
Observational study
STA1010 has 6 possible tutors: three female and three male. Each tutor takes one or more laboratories and each lab has only one tutor. A student allocates to only one group.
Event A = [the tutor is female #1] and
Event B = [the tutor is female #3].
These events are:
Each simple events
Shortly before a mayoral election, a market research firm took a poll to find out which candidate people were planning to vote for. The results are shown in the frequency table.
Li Fong: 2120
Bob Green: 2329
Sue Moore: 1042
Jose Alvarez: 399
Which of the following types of display would be more useful to show the difference in this data from candidate to candidate?
Select one: Bar Chart, Segmented Bar Chart, Pie Chart, XY Scatterplot or Histogram
Bar Chart
Which of the following statements is NOT true about the F-test in one-way analysis of variance?
- The numerator degrees of freedom = k-1 where k is number of groups in the study.
- An F-distribution is a symmetric distribution.
- The denominator degrees of freedom = N-k, where N is the total number of samples in all cases.
- The F-statistic can never be a negative number.
- The F-statistic is the ratio of MST to MSE.
An F-distribution is a symmetric distribution
Which one of the following probabilities is a “cumulative” probability?
- The probability that the total annual rainfall in Melbourne next year will be 65.1 cm.
- The probability that there are exactly 4 people with Type O+ blood in a sample of 10 people.
- The probability that a randomly selected woman’s height is 170 cm or less.
- The probability of exactly 3 heads in 6 flips of a coin.
- The probability that it takes 4 throws of a die to get a “6”.
The probability that a randomly selected woman’s height is 170 cm or less
Which of the following situations is an example of a binomial random variable?
- The number of coins a randomly selected student is carrying.
- The number of games your football team will win in this coming season.
- The number of brothers or sisters a randomly selected student has.
- The number of questions you would get correct on a multiple-choice test if you randomly guessed in all questions.
- The number of games your football team plays before it wins a game in the coming season.
The number of games your football team plays before it wins a game in the coming season.
In carrying out a two independent sample t-test for means, I have a choice of selecting “pooled” or “not pooled”.
If I select the “pooled” option, then I am assuming:
The population variances of the two groups are the same.
The maximum distance at which a highway sign can be read is determined for a sample of young people and a sample of older people. The mean distance is computed for each age group.
What is the most appropriate null hypothesis about the means of the two groups?
The population means of the two age groups are the same.
When comparing two means, the situation most likely to lead to a result that is statistically significant but of little practical importance is?
When the actual difference is small and the sample sizes are large.
A 95% confidence interval for the proportion p of voters supporting the Donkey Party was found to be (0.41, 0.47).
A one-proportion z-test will be carried out, with hypotheses
* H₀:p = 0.50 * Hₐ:p not = 0.50.
What decision can I make at a level of significance of 0.05?
Reject the null hypothesis
A random sample of 800 airline passengers is wanted from 100 particular flights leaving Sydney Airport.
Assume there are 200 passengers aboard each flight.
Simple random samples of 8 people could be drawn from the 200 passengers from each flight, resulting in a total sample of 800 passengers.
What type of sampling technique is this?
Stratified random sampling.
A man is on trial accused of murder in the first degree. The prosecutor presents evidence that he hopes will convince the jury to reject the hypothesis that the man is innocent. This situation can be modeled as a hypothesis test with the following hypotheses:
H₀: The defendant is not guilty.
Hₐ: The defendant is guilty.
Explain the result if a Type II error occurs.
The correct answer is: The jury will conclude that the defendant is not guilty when in fact he is guilty
