Showing posts with label standard deviation. Show all posts
Showing posts with label standard deviation. Show all posts

Monday, February 24, 2014

A Calculator can Come in Handy

Since my math class has been about statistics for the past few weeks, my whole class participated in an activity to test our knowledge. Our activity was to list the total dollars spent this semester for textbooks. Each student would write it on the white board and I was surprised on the variation. One student asked, ¨I didn't buy any, do I still go up?¨ It is very important to consider each data point in order to have an accurate sample even if the data entry is 0.

We then had to find the mean, standard deviation, median, mode, the lowest money spent, and the highest money spent. Luckily, calculators can also calculate these statistics. We all used the calculators and ended up having $243.86 as the average amount spent, but the standard deviation is $136.53. Since the standard deviation is pretty high the data varied greatly, meaning it may be best to look at either mode or median. In the end, the median was $225 and $350 for the mode. If we wanted to find an accurate sample, we would have to find more Mesa Community College students to participate. If you want to know how to calculate them in the calculator here is a link that gives you directions and meanings.

Saturday, February 22, 2014

The average always needs the standard deviation?

In statistics, the mean is always reported with the standard deviation. It is important to know the standard deviation in order to analyze the data. Now, what is standard deviation? Well it is the mean of the mean. Another way of explaining is that it measures how spread out the data is. For statisticians, the standard deviation determines if the experiment or the benefits works. For example, when conducting a research about the social behaviors of a person in an awkward situation, the psychologist would write down the data they received. With that information, they calculate the average of how people react in that sample. Once they find the average, they have to calculate the standard deviation to see if their predictions were correct or false.

When calculating the standard deviation by hand, we need to find the variance based off the mean. Variance is the measure of how far the numbers are from each other. In this website, it shows and how to calculate the variance and the standard deviation (sd). What is really important to understand is, the higher the sd is, the more spread out the data is, therefore most likely not accurate or not good depending in the situation. One example could be grades from a classroom test. If the average of the test was an seventy and the sd was a 10, it means that most of the scores were in between 60 and 80. This range is not very good considering that some really understand, but some might only understand the concept.