Warmup - Just put on notes page Determine whether the situation calls for a survey, an experiment, or an observational study. Explain your reasoning. MOVIES A production studio played a movie for a test audience and watched their reactions. A. Survey; members of the sample are observed and asked their opinions. B. Experiment; members of the sample are observed and affected by the study. C. Observational study; members of the sample are observed and unaffected by the study. D. Experiment; members of the sample are treated and affected by the study.

11-2 Distributions of Data Use the shapes of distributions to select the appropriate statistics Use the shapes of distributions to compare data

Population: Group of interest (review 0-9) Variable: characteristic of a population that can take on different values called data. Sample: used when it is not possible to observe data for every member of the population. Measures of central tendency are mean, median and mode. Sample mean

Q1 or lower quartile is the median of the lower half. Measures of position: Quartiles – three measures that divide data arranged in ascending order into 4 groups, each with about 25% of data. Q1 or lower quartile is the median of the lower half. Q3 is the median of the upper half. A number like 29 + 23 or 51 would be an outlier. The difference between Q3 and Q1 is called the interquartile range, IQR. The IQR contains 50% of the data. An outlier is a value that is beyond the upper or lower quartile by more than 1.5 times the interquartile range.

These can be shown with histograms. Distribution of data shows the observed or theoretical frequency of each possible data value. These can be shown with histograms. Left foot toes Right foot toes Both Feet

USE COMPLETE SENTENCES, NOT JUST A LIST! Rule of thumb: (Need to write this down!) When a distribution is symmetric, use mean and standard deviation to describe the data. When a distribution is skewed or has outliers, use the five number summary. Five number summary is: (1,2) The range from the minimum to the maximum (3) The median (4,5) The lower and upper quartiles and a mention that 50% of data values lies between them. Range from low to high, median, and Q1 and Q3 and that 50% of data lies between. USE COMPLETE SENTENCES, NOT JUST A LIST!

Refer to the TI-84 Quick Reference Sheet for steps Refer to the TI-84 Quick Reference Sheet for steps. You control the number of bins by choosing the window the data is displayed in. To see the histogram, select 2ND STAT PLOT, turn on, select Type: (looks like a mini histogram), Xlist should be the list where you put your data, most likely L1 and Freq:1. If you don’t like how it looks, change the window. When answering these questions, you need to transfer these histograms to your paper, indicate the window and scale you used, then answer rest.

Use a graphing calculator to create a histogram for each data set Use a graphing calculator to create a histogram for each data set. Then describe the shape of each distribution (use same window and scale) Compare the distributions using either the means and standard deviations or the five number summaries. Justify your choice.

11-2A p 738/ 1, 3, 7, 8, 14, 17, 21-23