# The Process of Statistical Analysis in Psychology

# Web Activities

Click on the following links. Please note these will open in a new window.

*Activity 1:*

*z* Score calculation review

Your book discusses how to calculate a *z* score. In this activity, you will review the requirements of *z* score calculations.

Using your preferred Internet search engine, try to find information about how much the average person does a behavior of your choice. Examples include:

- cereal eaten per year,
- money spent on coffee per month,
- shirts owned, and
- went grocery shopping.

Ask yourself the following questions:

- Can you find information on the average?
- Can you find information on the standard deviation?
- Can you calculate a
*z*score based on the information you have? Why or why not? - What information would you need to calculate a standard deviation?

*Activity 2:*

**Visualizing z scores and percentile ranks**

Your book discusses how *z* scores correspond to percentile ranks. It can be difficult to visualize this correspondence--in this activity you will.

For this activity, you will need a smartphone. Download the PAR Toolkit app (free for either android or iPhone). Go to the Normal curve tab. Think of several different percentile ranks and *z* scores (three of each). Enter these into the respective boxes by tapping on them. Observe how the blue area of the normal curve at the top changes with the values you put in for *z* scores, and how the *z* score changes with the values you put in for percentiles.

*Activity 3:*

*z*** Score and percentile rank calculation**

Your book discusses the relation between *z* scores and percentile ranks. In this activity, you will apply this information in a new way.

The information in this activity was obtained from https://www.cdc.gov/nchs/data/series/sr_11/sr11_252.pdf

Answer the following questions using the area under the curve table in your book. Assume a normal distribution.

- Females 20+ years old have an average weight of 166.2 pounds. A person at the 5th percentile = 110.7 pounds. What is the standard deviation?

- First, what is the
*z*score of the 5th percentile? - Input the
*z*score into the*z*score equation along with the mean - Calculate

- First, what is the
- Males 20+ years old have an average weight of 195.5 pounds. A person at the 75th percentile is 218.0 pounds. What is the standard deviation?

- First, what is the
*z*score of the 5th percentile? - Input the
*z*score into the*z*score equation along with the mean - Calculate

- First, what is the