Statistics Midterm

what is a frame?

a frame is a list of the individuals in the population being studied.

define simple random sampling.

a sample of size n from a population of size N is obtained through simple random sampling if every possible sample of size n has an equally likely chance of occurring. the sample is then called a simple random sample.

classes

are the categories by which data are grouped

what does it mean if a statistic is a resistant?

extreme values (very large or small) relative to the data do not affect its value substantially.

what is the difference between univariate data and bivariate data?

in univariate data, a single variable is measured on each individual. in bivariate data, two variables are measured on each individual.

a club wants to sponsor a panel discussion on the upcoming national election. the club wants four of its members to lead the panel discussion. write a short description of the processes that can be used to generate your sample. obtain a simple random sample of size 4 from the table.

list each name on a separate piece of paper, place them all in a hat, and pick four. number the names from 1 to 25 and use a random number table to produce 4 different two digit numbers corresponding to the names selected.

the _____ class limit is the smallest value within the class and the _____ class limit is the largest value within the class

lower; upper

if the linear correlation between two variables is negative, what can be said about the slope of the regression line?

negative

nation of origin

nominal

what does it mean when sampling is done without replacement?

once an individual is selected, the individual cannot be selected again.

movie ratings of one star through five stars

ordinal

_____ divide data sets in fourths

quartiles

in a boxplot, if the median is to the left of the center of the box and the right whisker is substantially longer than the left whisker, the distribution is skewed _____

right

write a short description of the process you used to generate your sample with statcrunch and use the seed 12652.

select data then simulate > discrete uniform. fill out rows: 10, columns: 1, minimum: 1 and maximum: 32. select the ratio button for use fixed seed and enter the seed 12652. choose names from the resulting sample by matching the first 4 distinct numbers with the row numbers of the names.

the closer r is to +1, the _____ the evidence of is of _____ association between the two variables.

stronger; positive

which z-score is better?

the lower one

which of the following is true of the least-squares regression line yhat= b1x + b0

the sign of the linear correlation coefficient, r, and the sign of the slope of the least-squares regression line, b1, are the same. the least-squares regression line always contains the point (x-bar, y-bar). the least-squares regression line minimizes the sum of squared residuals. the predicted value of y, y-hat is an estimate of the mean value of the response variable for that particular value of the explanatory variable.

there is not one particular frequency distribution that is correct, but there are frequency distributions that are less desirable than others.

the statement is true. any correctly constructed frequency distribution is valid. however, some choices for the categories or classes give more information about the shape of the distribution.

dogs are randomly divided into two groups. one group is trained using food as a reward; the other is trained using sound cues. after 2 months, each group is taught a new skill to compare obedience.

the study is an experiment because the researchers control one variable to determine the effect on the response variable.

a study is conducted to determine if there is a relationship between stomach cancer and alcohol consumption. everyone treated at a hospital for stomach cancer was asked about their alcohol consumption.

the study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.

what does it mean to say that two variables are negatively associated?

there is a linear relationship between the variables, and whenever the value of one variable increases, the value of the other variable decreases.

what does it mean to say that two variables are positively associated?

there is a linear relationship between the variables, and whenever the value of one variable increases, the value of the other variable increases.

the _____ represents the number of standard deviations an observation is from the mean

z-score