Unit 1 Stats

preventing either the subjects or the researchers from knowing whether they are assigned to the control group or the treatment group, usually by using a placebo in experiments involving humans

Blinding

a graph that consists of contiguous (adjoining) boxes, and can show you the shape, the center and the spread of the data.

Histogram

a type of graph where a circle is divided into sectors, or slices, which each show the proportion of that subcategory compared to the whole may also be referred to as a Pie graph or a Circle graph

Pie chart

the treatment that cannot influence the response variable

Placebo treatment

the affected variable, the variable that is changed by altering the explanatory variable In some circumstances, the Response variable may be referred to as the Dependent variable, the Outcome variable, or the Output variable

Response variable

What is the natural variation that results from selecting a sample to represent a larger population?

Sampling error

A sampling bias is defined as _______.

the situation in which not all members of the population are equally likely to be selected

Which of the following sets of data should not be displayed with a pie chart? Assume that only the two given categories will be included.

the percentage of people who have a full-time job and the percentage of people who have a part-time job

Which of the following sets of data should not be displayed with a pie chart? Assume that only the two given categories will be included.

the percentage of people who like horror films and the percentage of people who like romantic dramas

When considering different sampling methods, cluster sampling includes the steps: _______.

use simple random sampling to select a set of groups; every individual in the chosen groups is included in the sample

A researcher is interested in the effects of watching videos just before bed on the quality of sleep. He has decided to test the claim "Watching 1 hour of video just before going to bed reduces the number of minutes of REM sleep by more than 10%. " Which of the following data collection processes would be appropriate? Select only one answer choice.

Choose a random sample of people. On multiple randomly selected nights, randomly assign each person to either watch one hour of video or not watch video and monitor their sleep.

Annie wants to estimate the average number of AP classes a student at her high school takes. She decides to randomly select 6 classes and use all the students in those 6 classes to estimate the average. What type of sampling did Annie use?

Cluster Sampling

A nonsampling error is an issue that affects the reliability of sampling data other than natural variation.

True

Patrick is collecting data on shoe size. What type of data is this?

discrete quantitative

Which of the following scenarios contains a sampling error?

A study is conducted to determine the favorite subject of all the students in your high school. Students in your homeroom class were used as the sample

Which of the following sampling scenarios describe convenience sampling?

An administrative assistant was asked to stand in front of the library one Wednesday and ask the first 100 undergraduate students he encountered what they paid for tuition for the Fall semester. Those 100 students were the sample.

the group set aside to receive the placebo treatment

Control group

attempts to explain or influence changes in another variable In some circumstances, the Explanatory variable may be referred to as the Independent variable, the Input variable, or the Predictor variable

Explanatory variable

different values of the explanatory variable

Treatment

A study is planned to research the effects of drinking coffee on hours of sleep. Would an experimental or observational study design be more appropriate?

An experimental study should be used where the consumption of coffee is the experimental factor.

An energy drink manufacturer wants to find out the effect of different amounts of their product on the maximum anaerobic power level for rowers. Would an experimental or observational study design be more appropriate?

An experimental study should be used with the amount of the drink consumed as the controlled factor.

A researcher wants to evaluate the effect of using Facebook on happiness. Would an experimental or observational study design be more appropriate?

An experimental study should be used with the use of Facebook as the controlled factor.

a graph to summarize and organize categorical data consisting of rectangular bars that are separated from each other and the length (or height) of the bar for each category is proportional to the number or percent of individuals in each category may also be referred to as a Bar chart

Bar graph

Angela is studying the mean blood pressure of all students attending her college. She collects data from the 38 students in her statistics class. Which type of sampling is used?

Convenience sampling

one where both the subjects and the researchers are blinded

Double-blind experiment

data measured this way have a definite order and the difference between these data can be measured, but do not have a starting point Ex: celsius temperature scale

Interval scale

Which of the following scenarios demonstrates sampling bias?

Kathryn wants to estimate the mean amount of money spent on clothes per week by mall shoppers. She collects data from every 10th person entering a clothing store at the mall.

a bar graph with the tops of the bars represented by points joined by lines (with rest of the bar not shown) and are only appropriate for ordered (rather than qualitative) variables that show how a quantity changes over time may also be referred to as a Line chart or as a Time series graph

Line graph

additional variables that can cloud a study's outcome In some cases, the Lurking variable may be referred to as a Confounding variable, Confounding factor, or simply as a Confounder

Lurking variable:

Given the following list of values, is the mean or the median likely to be a better measure of the center of the data set? 35, 39, 37, 37, 38, 34, 35, 37, 65

Median

A statistics student is doing a project for her class. She wants to make a prediction for the outcome of an upcoming national election. Since there are only two candidates, she decides that her question is "Which candidate do more people favor in the upcoming election?" She decides to randomly interview 100 students crossing the courtyard on campus about their preference. Is this sample good for drawing general conclusions about the results of the election?

No. The results are not generalizable because the students at her school are not representative of the population of all voters.

data measured this way are qualitative and not ordered or ranked Ex: favorite sport/pizza topping, ethnicity, shape

Nominal scale

data measured this way can be ordered or ranked Ex: agreement scale

Ordinal scale

the result of categorizing or describing attributes of a population, usually described by words or letters referred to as categorical data

Qualitative data

the result of counting or measuring attributes of a population, always described by numbers

Quantitative data

data measured this way have a definite order and starting point, and the difference between these data can be measured Ex: money, length, mass, volume

Ratio scale

Sneha wants to inspect the cleanliness of the rooms in a hotel. There are 10 floors in the hotel and each floor has 20 rooms. From each floor, she randomly selects 2 rooms and inspects them. What type of sampling did Sneha use?

Stratified Sampling

A candy manufacturer is interested in the distribution of colors in each of its packages of candy sold. The manufacturer wants to answer the question "What is the typical distribution of colors in a package of candy?" Which data collection method should be used?

The manufacturer should randomly sample packages at the factory over multiple batches and determine the distribution in each package.

A biology student is interested in the relationship between temperature and germination time for soy beans. The student gets sample seeds from multiple sources and randomly selects 180 seeds from them. Then he sets up three growing stations, one at 20∘C, one at 15∘C, and one at 25∘C. He divides the seeds into three groups of 60 and plants the seeds from each group in a growing station. He records the germination time for each seed. Is this an observational study or an experiment? If it is an experiment, what is the controlled factor?

The study is an experiment. The controlled factor is the temperature.

An opinion poll was conducted to know whether parents play a role in shaping a career for their children. Respondents were asked to vote "Yes" if they think parents have a role to play and "No" if they think parents have no role to play in shaping the career of their children. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an observational study.

Is a survey of the guests about their preference of food at a party an observational study or experimental study? If it is an experiment, what is the controlled factor?

The study is an observational study.

A candy manufacturer is interested in the distribution of colors in each of its packages of candy sold. Which question is appropriate for their research?

What is the typical distribution of colors for the packages of candies?

A 2013 study at Johns Hopkins University wanted to measure if caffeine has an effect on short term memory. The researchers showed images to a group of people. They then gave half the group a 200-mg caffeine pill and the other half a placebo pill containing no caffeine. A day later they measured how many images each person could remember. What is the explanatory variable in this experiment?

Whether or not a person received caffeine

There are more people who volunteer in soup kitchens in the state of California than in the state of Arizona. Therefore, the people of the state of California are more willing to volunteer their time than the people of Arizona.

Yes, there is a problem with the logic. California has more residents than Arizona, therefore there is a likelihood that there will be more volunteers in soup kitchens as well.