Concept Quiz Ch. 1-3 True/False

A primary use of inferential statistics is to make generalizations from a sample to a proportion. True False

Answer: True Statistics is about making inference from a sample to a population. For example, the SAT average for a random sample of 10,000 students should be close to the true population average.

The relative frequency for a particular category is the number of times the category appears in the data. True False

Answer: b) False The relative frequency is a percent. The number of times the category appears in the data is just the frequency…not the “relative” frequency.

3. Bar charts should be used only with categorical data. True False

Answer: True Bar charts are for categorical data. Histograms are for quantitative data.

A pie chart is most useful for numerical data. True False

Answer: b) False Pie charts are for categorical data only. Think of creating a daily budget. What would be in your pie chart? Food, car, entertainment, college savings, etc. These are categories.

5. A segmented bar chart displays the marginal distribution of a categorical variable. True False

Answer: b) False A segmented bar chart displays the conditional distribution of a categorical variable within each category of another variable. From the graph above, we can determine from those who allow, 43% percent had success.

When collecting data, a number always represents quantitative data. True False

Answer: b) False Think of your student number, this is a categorical variable. A measurement such as height, weight, or age is quantitative. However, even a quantitative variable such as age is categorical if on a survey you are asked in which age group you lie.

Based on the graphs below, the variables are considered to be independent. True False

Answer: b) False Remember “independent” means “no association” or “the same.” Dependent means different. The graphs are different so the variables are dependent meaning there is a relationship between the variables. One does affect the other.

8. Based on the graphs below, the variables are considered to be dependent.

Answer: True The graphs are different, so there is a dependent relationship between education level and whether a person smokes.

Using the table below, a question that would elicit a marginal frequency as an answer would be: “What percent of students ride the bus to school?” True False

Answer: a) True Marginal frequencies are calculated by either (row total)/(grand total) or (column total)/(grand total). So, the percent of students who ride the bus to school would be 64/188.

A conditional frequency question and answer would be exemplified by the following: What percent of students ride the bus and are female? The answer would be 34/188. True False

Answer: b) False This is a joint frequency question and answer which is calculated by (bus and female)/(grand total) = 34/188 A conditional frequency question would be, of those who ride the bus, what percent are female. This would be calculated by (bus and female)/(bus total) = 34/64