Chap 5 review quiz

What is the distinction between qualitative data and quantitative​ data? Give a few examples of each.

Qualitative data describe​ categories, while quantitative data represent counts or measures. Brand names of shoes in a consumer survey and eye colors are examples of qualitative data. Heights of students and quiz scores are examples of quantitative data.

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Create a table. What is the Grade Frequency? Relative Frequency? Cumulative Frequency? Total?

How can the graphics sometimes be​ useful?

It can make it easier to show small scale trends in the data.

Briefly describe each of the six guidelines for establishing causality.

The first guideline states that one should look for situations where the effect is correlated with the suspected​ cause, even when other factors vary. The second guideline states that among groups that differ only in the presence or absence of the suspected​ cause, one should check that the effect is similarly present or absent. The third guideline states to look for evidence that larger amounts of the suspected cause produce larger amounts of the effect. The fourth guideline states that if the effect might be produced by other potential​ causes, make sure the effect still remains after accounting for these other potential causes. The fifth guideline states that the suspected cause should be tested with an experiment.The sixth guideline states that the physical mechanism by which the suspected cause produces the effect should be determined.

How do we determine the strength of a​ correlation?

The more closely two variables follow the general​ trend, the stronger the correlation​ (which may be positive or​ negative).

What is a​ correlation? Give three examples of pairs of variables that are correlated.

A correlation exists between two variables when higher values of one variable consistently go with higher or lower values of another variable. amount of smoking and lung​ cancer, height and weight of​ people, price of a good and demand of the good.

What two types of graphs are most common when the categories are qualitative​ data? Describe the construction of each.

In a bar​ graph, the categories are clearly indicated along the horizontal axis. Over each category is a rectangle whose height indicates the frequency or relative frequency of the category. Numbers along the vertical axis clearly indicate the scale. In a pie​ chart, each category corresponds to a wedge of a circle. The size of each wedge is proportional to the relative frequency of the category it represents.

Choose the correct construction and use of multiple bar graphs

It is a simple extension of a regular bar graph. It has two or more sets of bars that allow comparison of two or more data sets. The data categories are qualitative.

Choose the correct construction and use of multiple line charts

It is a simple extension of a regular line chart. It uses different lines for different data​ sets, each based on a different level. The data categories are quantitative.

the correct construction and use of stack plots

It shows different data sets stacked in both bar graphs and line charts It uses stacked bars laid out horizontally. Each bar is divided into​ sections, which are​ color-coded according to the legend at the top. It is made with stacked​ lines, which are particularly useful for showing trends over time.

Define negative correlation.

Negative correlation means that two variables tend to change in opposite​ directions, with one increasing while the other decreases.

Define no correlation.

No correlation means that there is no apparent relationship between the two variables.

There is a strong correlation between tobacco smoking and incidence of lung​ cancer, and most physicians believe that tobacco smoking causes lung cancer.​ However, not everyone who smokes gets lung cancer. Briefly describe how smoking could cause cancer when not all smokers get cancer.

Not all smokers get cancer because cancer is caused by cell​ mutation, and while smoking increases the chances of such a mutuation​ occuring, the mutation does not occure in every smoker.

Define positive correlation

Positive correlation means that both variables tend to increase​ (or decrease) together.

Describe the importance of labeling on a​ graph, and briefly discuss the kinds of labels that should be included on graphs.

The graph should have a title or caption​ (or both) that explains what is being shown​ and, if​ applicable, lists the source of the data. Without this​ label, it might not be clear what the graph is supposed to illustrate. Your answer is correct. Numbers along the vertical axis should clearly indicate the​ scale, and there should be a label that describes the variable shown on the vertical axis. Without either of​ these, there would be no way of interpreting the data shown in the graph. If multiple data sets are displayed on a single​ graph, there should be a legend or key to identify the individual data sets.​ Otherwise, comparisons among the data sets would not be possible and confusion among the data sets could occur.

Decide whether the following statement makes sense​ (or is clearly​ true) or does not make sense​ (or is clearly​ false). Explain your reasoning. My bar chart contains more information than​ yours, because I made my bars​ three-dimensional.

The statement does not make sense because making the bars​ three-dimenional does not necessarily mean that information was added. It could mean that only the appearance of the graph was changed.

Decide whether the following statements makes sense​ (or is clearly​ true) or does not make sense​ (or is clearly​ false). Explain your reasoning. I made a frequency table with two​ columns, one labeled​ "State" and one labeled​ "State Capitol."

The statement does not make sense. In a frequency​ table, one of the columns lists the frequency of each​ category, which is the number of data values in the category. The table described in the given statement does not have this column.

Decide whether the following statement makes sense​ (or is clearly​ true) or does not make sense​ (or is clearly​ false). Explain your reasoning. Your pie chart must be​ wrong, because when I added the percentages on your​ wedges, they totaled​ 124%.

The statement makes sense because pie charts are used primarily for relative​ frequencies, so the total pie must always represent the total relative frequency of​ 100%

Decide whether the following statement makes sense​ (or is clearly​ true) or does not make sense​ (or is clearly​ false). Explain your reasoning. ​There's been only a very slight rise in our stock price over the past few​ months, but I wanted to make it look dramatic so I started the vertical scale from the lowest price rather than from zero.

The statement makes sense because reducing the range of the vertical axis to just fit the data will increase the relative size of the variation in the data.

I had originally suspected that an increase in variable E would cause a decrease in variable​ F, but I no longer believe this because I found no correlation between the two variables.

The statement makes sense. ​Originally, a negative correlation was suspected. Since no correlation was​ found, there is apparently no relationship between the variables.

How can the graphics sometimes be​ misleading?

The variation can seem to be larger than it really is.

Explain how a graph that shows percentage change can show descending bars​ (or a descending​ line) even when the variable of interest is increasing.

The vertical axis on the graph represents a percentage change such that the​ drop-off means only the actual value of the variable rises by smaller amounts.

Consider the following statement about a correlation. State the correlation clearly​ (for example, there is a positive correlation between variable A and variable​ B). Then state whether the correlation is most likely due to​ coincidence, a common underlying​ cause, or a direct cause. Explain your answer. In a large resort​ city, the crime rate increased as the number of taxi cabs increased.

There is a positive correlation between the crime rate and the number of taxi cabs. This correlation is due to a common underlying cause because it is possible​ that, with an increase in​ tourism, both the crime rate and the number of cabs increase.

Consider the following statement about a correlation. State the correlation clearly​ (for example, there is a positive correlation between variable A and variable​ B). Then state whether the correlation is most likely due to​ coincidence, a common underlying​ cause, or a direct cause. Explain your answer. Automobile gas mileage decreases with tire pressure.

This correlation is due to a direct cause because more gasoline is needed to roll a tire with lower pressure.

Suppose that people living near a particular​ high-voltage power line have a higher incidence of cancer than people living farther from the power line. Can you conclude that the​ high-voltage power line is the cause of the elevated cancer​ rate? If​ not, what other explanations might there be for​ it? What other types of research would you like to see before you conclude that​ high-voltage power lines cause​ cancer?

You cannot conclude that the power line is the cause of the elevated cancer rate because cause cannot be established until a mechanism is confirmed.A study that determines the effect of electricity on a​ cell's growth mechanism.