Business Analytics ch:2

For data having a bell-shaped distribution, approximately _____ percent of the data values will be within one standard deviation of the mean. a. 97 b. 66 c. 95 d. 68

68

The results of a national survey showed that on average, adults sleep 7.1 hours per night. Suppose that the standard deviation is 1.5 hours and that the number of hours of sleep follows a bell-shaped distribution. If needed, round your answers to two decimal digits. If your answer is negative use "minus sign". (a) Use the empirical rule to calculate the percentage of individuals who sleep between 4.1 and 10.1 hours per day (b) What is the z-value for an adult who sleeps 8 hours per night? (c) What is the z-value for an adult who sleeps 6 hours per night?

95.44% 0.6 -.73

Random sampling

A sampling method to gather a representative sample of the population data. -Every entity in that target population has the same chance of being in the sample . The way that we dont get a bias sample.

Frequency distribution

A summary of data that shows the number(frequency) of observations in each of several non overlapping classes .• Typically referred to as bins, when dealing with distributions. How many

Relative frequency distribution

A tabular summary of data showing the relative frequency for each bin. Proportion or probability RF = f/n

Experimental study

A variable of interest is first identified. - Then one or more other variables are identified and controlled or manipulated so that data can be obtained about how they influence the variable of interest

Population

All elements of interest.

Cross-sectional data

Data collected from several entities at the same, or approximately the same, point in time.

Time series data

Data collected over several time periods. • Graphs of time series data are frequently found in business and economic publications. • Graphs help analysts understand what happened in the past, identify trends over time, and project future levels for the time series

Quantitative data

Data on which numeric and arithmetic operations, such as addition, subtraction ,multiplication, and division, can be performed Variable telling you how much or how many

Categorical data:

Data that consists of names, labels, or other nonnumerical values -Data on which arithmetic operationscannot be performed.

Non-experimental study or observational study:

Makes no attempt to control the variables of interest. A survey is perhaps the most common type of observational study

Percent frequency distribution

Summarizes the percent frequency of the data for each bin. PF = RF * 100

Sample

a subset of the population

Which of the following are necessary to be determined to define the classes for a frequency distribution with quantitative data? a. Number of nonoverlapping bins, width of each bin, and bin limits b. Width of each bin and bin lower limits c. Width of each bin and number of bins d. Number of overlapping bins, width of each bin, and bin upper limits

a. Number of nonoverlapping bins, width of each bin, and bin limits

A _____ determines how far a particular value is from the mean relative to the data set's standard deviation. a. z-score b. percentile c. variance d. coefficient of variation

a. z-score

The distribution of hourly sales for a local family owned store is normally distributed with a mean of $225 per hour and a standard deviation of $75 per hour. Which of the following intervals contains the middle 95% of hourly sales? . $150 to $300 b. $75 to $375 c. $125 to $325 d. $175 to $275

b. $75 to $375

What type of vehicle are you considering for your next purchase? Nine response categories include sedan, sports car, SUV, minivan, and so on.

categorical

When did you first start reading the WSJ? High school, college, early career, midcareer, late career, or retirement?

categorical

are you male or female

categorical

_____ are collected from several entities at the same point in time.

cross-sectional data

The _____ shows the number of data items with values less than or equal to the upper class limit of each class. a. percent frequency distribution b. frequency distribution c. relative frequency distribution d. cumulative frequency distribution

d. cumulative frequency distribution

A set of values corresponding to a set of variables is defined as a(n) _____.

observation

A Wall Street Journal subscriber survey asked 46 questions about subscriber characteristics and interests. State whether each of the following questions provides categorical or quantitative data. (a)What is your age?

quantitative

How long have you been in your present job or position?

quantitative

_____ acts as a representative of the population.

sample

The _____ is a point estimate of the population mean for the variable of interest.

sample mean

When working with large spreadsheets with many rows of data, it can be helpful to _____ the data to better find, view, or manage subsets of data.

sort and filter

Target population:

take a small subset called a sample.. We use sample bc it saves us time and money. Another reason is bc sometimes its just not practical to use the population.. ex: medical testing, how many hours does motor in microwave last (be better w/ small group of microwaves)