Frequency Distribution and Motor Vehicle-Related Deaths

Frequency distribution for diabetes patient's fasting plasma glucose levels

1. People with diabetes must monitor and control their blood glucose levels. The goal is to maintain “fasting plasma glucose” between 90 and 130 milligrams per deciliter (mg/dl). Here are the fasting plasma glucose levels for 18 diabetics enrolled in a diabetes control class, 5 months after the class has ended.

a. Make a Frequency distribution filling in the table below  using the following class intervals   

Frequency is the number of observations that fall into the class interval

Relative Frequency is the percentage of the total observations that fall into the class interval

b. Using the Frequency distribution in part b,draw a histogram and be sure to label the X and Y axes.

2. The Morbidity and Mortality Weekly Report (MMWR ) series is prepared by the Centers for Disease Control and Prevention (CDC).  The intended audience consists of physicians, nurses, public health practitioners, researchers, educators, and laboratorians.

The following bar graph is from an article on Motor vehicle-related deaths published in a supplement to MMWR titled CDC Health Disparities and Inequities report (January 14, 2011).

If you are interested in accessing the full report go to  http://www.cdc.gov/mmwr/preview/ind2011_su.html

Motor vehicle--related death rates, by sex and race/ethnicity --- from National Vital Statistics System, United States, 2007.

a. Based on the bar graph which sex and race/ethnic group are at highestrisk for Motor vehicle death.

b. Overall, across all the racial/ethnic groups, are men or women more likely to suffer a motor vehicle death?

c. What do you think is meant by the label of the y-axis---“age-adjusted”death rate per 100,000?

d. Why is there no need for sexor race to adjust these data?

3. In each of the following, give a brief description of the population under study and then indicate how the sample that is chosen may be biased(unrepresentative of the population).

a. A psychologist wishes to study the relationship between aggressiveness and social popularity among college students. She places an advertisement in the campus newspaper requesting volunteers to participate in the study.

b. A sociologist asks whether the incidence of crimes in the US committed by adolescents decreases when school is in session (months between September and June). With the cooperation of the police departments in Minneapolis, Chicago, and Atlanta he collects monthly statistics on crimes committed by adolescents in those cities during the preceding three years.

Histogram of fasting plasma glucose levels for diabetes patients

c. Suppose this same sociologist aggregates the data from the 3 cities and uses the aggregated data to assess the relationship between crimes and seasonality.

4. Indicate for each of the following variables whether it is quantitative or qualitative and if quantitative whether it is continuous or discrete and if qualitative whether it is ordinal or nominal.

Strength of opinion (1-10 scale strongly agree to strongly disagree)

Color of hair

Shade of hair color

Temperature

Systolic blood pressure

Number of murders in Atlanta in 2001

Proportion of murders with female victims

5. Parameter or Statistic? In the examples below identify if the numerical summary is considered a parameter or a statistic/estimator?

A landmark tax bill was passed in December 2017 with 51% of US senators voting for the bill.  Is 51% a parameter or a statistic?

The Kaiser Health Tracking Poll asked: “As you may know, a health reform bill was signed into law in 2010. Given what you know about the health reform law, do you have a generally favorable or generally unfavorable opinion of it?” Based on the results of this poll, 50% of the US residents have a favorable opinion. Is 50% a parameter or a statistic?

In 2015, based on the data from the United States Office of Personnel Management the median salary of permanent, full-time, non-seasonal federal employees was $76,131. Is $76,131 a parameter or a statistic for federal salaries in 2015?

An article states, 30% of dog owners poop scoop after their dog. Is 30% a parameter or a statistic?

6. For each experiment identify the dependent and independent variables. Also, indicate whether each variable is quantitative or qualitative and if quantitative whether it is continuous or discrete, and if qualitative whether it is ordinal or nominal.

To test the theory that vitamin C can ward off developing colds, a randomized placebo-controlled study is designed to compare daily 1000 mg dose of vitamin C to a placebo group and assess whether each individual develops at least one cold during a 4-month period.

Based on data available from a large nationally representative cross-sectional study, a research question is developed to examine the association between vitamin C intake and developing colds. In order to do this, self-reported dietary and supplement intake of vitamin C (in milligrams) is evaluated for each individual as well as the annual frequency of self-reported colds.

Which study design (a or b) is better suited to establish causality between vitamin C levels and developing colds?