Statistics Experiment Design

A p-value of P=0.05 means

• there is a 0.05% probability the results are due to chance

• there is a 0.5% probability the results are due to chance

• there is a 50% probability the results are due to chance

• there is a 5% probability the results are due to chance

Which test requires a repeated measures design?

• Chi squared

• Spearman's Rho

• Mann Whitney U

• Wilcoxon T test

In the previous problem, supposed that the researchers suspected that women over the age of 55 may respond differently to the treatment. Given that a random sample of 40,000 women over the age of 45 has already been chosen, the study would have been improved by:

• a stratified sample, with strata determined by age.

• a stratified sample, with strata determined by gender.

• a block design, with blocks determined by age.

• a block design, with blocks determined by gender.

• a double-blind completely randomized design.

Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Studies indicate that about 93% of the population may be characterized as right-handed. Researchers would like to conduct a study to determine if left-handed teens differ significantly in their ability to memorize facts than right-handed teens. Suppose the researchers concluded that the average number of words memorized by left-handed teens was statistically significantly higher than the average number memorized by right-handed teens. In this context, statistically significant means that:

• the number of words memorized by left-handed students exceeded the number memorized by right-handed students.

• the average number of words memorized by left-handed students exceeded the average number memorized by right-handed students.

• right-handed students tend to not do as well as left-handed students in memorizing words.

• it would be unlikely to observe an average difference as large as was observed by chance variation.

• a randomized, controlled experiment was conducted.

What type of study is described? A gym tries out a new weightlifting method to see if it will build muscle for their customers faster than their current method.

• Sample Survey

• Experiment

• Observational Study

A ​ (a)   should include

the following:

a. ​ (b)   of at least two treatment

groups, one of which could be a

control group.

b. ​ (c)   assignment/allocation of

treatments to experimental units.

c. ​ (d)   (more than one experimental

unit in each treatment group).

d. ​ (e)   of potential confounding variables

where appropriate

• well-designed experiment

• Comparisons

• Random

• Replication

• Control

This branch of statistics that deals with designing statistical experiments is called ________.

• Descriptive Statistics

• Inferential Statistics

• Experimental Design

A fast-food company advertises that the pre-cooked weight for its burgers is, on average, 0.2 kg. The company runs a regular quality control test that involves weighing a sample of burgers to see if the burgers are too light or too heavy. If the sample mean weight is significantly different than 0.2kg, then they recycle the entire batch. Choose the correct null and alternative hypotheses.

• Null hypothesis: average weight of the burgers in the sample = 0.2kg
  Alternate Hypothesis: average weight of the burgers in the sample do not equal 0.2kg

• Null hypothesis: average weight of the burgers in the sample do not equal 0.2kg
  
  Alternate Hypothesis: average weight of the burgers in the sample equal 0.2kg

• Null hypothesis: average weight of all burgers in the batch do not equal 0.2kg
  
  Alternate Hypothesis: average weight of all burgers in the batch equal 0.2kg

• Null hypothesis: average weight of all burgers in the batch equal 0.2kg
  
  Alternate Hypothesis: average weight of all burgers in the batch do not equal 0.2kg

A newspaper report claims that 30% of all tea-drinkers prefer green tea to black tea. Leo is the office manager at a company with thousands of employees. He wonders if the newspaper’s claim holds true at his company. To find out, Leo asks a simple random sample of 125 tea-drinking employees which they prefer: green tea or black tea.

Here's Leo's null hypothesis:

H0:The proportion of all tea-drinkers at the company that prefer green tea to black tea is...

What is an appropriate way for Leo to finish his null hypothesis?

• ...not equal to 30%

• ... equal to 30%

• ... less than 30%

• ... greater than 30%

This deliberately imposes some treatment on individuals to measure their responses.

• explanatory variable

• response variable

• factor

• experiment