# chi square

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False

### When we carry out a chi-square test for independence, the null hypothesis states that the tow relevant classifications.

D. The alternative hypothesis states that the two classifications are statistically independent
NOT If ri is the row total for row i and cj is the column total for column j, then the estimated expected cell frequency corresponding to row i and column j equals ricj/n.
The chi-square test is valid if all of the estimated expected cell frequencies are at least 5.
The chi-square statistic is based on (r-i) (c-i) degrees of freedom where r and c denote the number of rows and columns respectively in the contingency table.
None of the above.

### Which of the following statements about the chi-square test of independence is false? The alternative hypothesis states that the two classifications are statistically independent.

NOTIf ri is the row total for row i and cj is the column total for column j, then the estimated expected cell frequency corresponding to row i and column j equals ricj/n.
The chi-square test is valid if all of the estimated expected cell frequencies are at least 5.
The chi-square statistic is based on (r-i) (c-i) degrees of freedom where r and c denote the number of rows and columns respectively in the contingency table.
None of the above.

True

True

False

True

### In performing a chi-square test of independence, as the difference between the respective observed and expected frequencies decrease, the probability of concluding that the row variable is independent of the column variable

Correct: increases
NOT decreases
may decrease of increase depending on the number of rows and columns.
remains the same.

### A chi-square goodness of fit test is considered to be valid if each of the expected cell frequencies is ___________________.

E. at least 5.
NOT
greater than zero.
less than 5.
between 0 and 5.
at most 1

correct: 20
NOT 30 24 5 25

### The chi-square goodness of fit test is _________ a one-tailed test with the rejection point in the right tail.

Yes always NOT sometimes or never

correct 3
NOT 4999 6 5 4

### The process of using sample statistics to draw conclusions about true population parameters is called: Statistical inference The process of using sample statistics to draw conclusions about true population parameters is called:

Statistical inference

### The classification of student class designation (freshman, sophomore, junior, senior) is an example of:

Categorical random variable

### To monitor campus security, the campus police office is taking a survey of the number of students in a parking lot each 30 minutes of a 24-hour period with the goal of determining when patrols of the lot would serve the most students. If X is the number of students in the lot each period of time, then X is an example of:

a discrete random variable

### The personnel director at a large company studied the eating habits of the company's employees. The director noted whether employees brought their own lunches to work, ate at the company cafeteria, or went out to lunch. The goal of the study was to improve the food service at the company cafeteria. This type of data collection would best be considered as:

an observational study

30

50

mode

### Which of teh following is NOT a measure of central tendency?

interquartile range

20%

0.733

81

7.00

### A professor receives, on average, 24.7 e-mails from her students per 24 hour period on the day before the midterm exam. To compute the probability of receiving at least 10 e-mails on such a day, what type of probability distribution should be used?

Poisson distribution

1.16

1.00

### If a particular batch of data is approximately normally distributed, we would find that approximately

2 of every 3 observations would fall between 1 standard deviation above and below the mean.
4 of every 5 observations would fall between 1.28 standard deviation above and below the mean.
19 of every 20 observations would fall between 2 standard deviation above and below the mean.
ALL OF THE ABOVE

0.0228

Weight # Jars
8.0 oz. 300
8.5 oz. 287
8.9 oz. 128
9.0 oz. 67

0.1366

### There are 5 starting players on the Bulldog basketball team. Each player wanted to improve her shooting percentage, especially Hannah. The number of baskets Hannah made in the last 10 games are listed below: 12,13,21,18,19,8,4,22,12,27

Calculate the mean, median, mode, variance and standard deviation and range and list them in that order.
15.6, 15.5, 12, 49.16, 7.01, 23

### The width of a confidence interval estimate for a proportion will be:

narrower for 90% confidence than for 95% confidence

2.7969

False

True

### A major department store chain is interested in estimating the average amount its credit card customers spent on their first visit to the store. 85 accounts were randomly selected. The 95% confidence interval was \$56.89 t0 \$145.78. Therefore, the store manager can be 95% confident that

most of his customers are spending more than \$50

rejected

False

### How many Kleenex should a Kimiberly Clark Corp. package of tissues contain? Researchers determined that, on average, a person uses 60 tissues during a cold, and the population standard deviation is 22. Suppose a random sample of 100 Kleenex users yielded a mean of 52. Test the following hypothesis at the 5% significance level.

Critical Value = 1.96; Calculated Z = 3.64; Reject the null hypothesis

False

[63.43 to 64.17]

6

True

### A manufacturing company produces bike frames and makes 1200 per year. These bike frames can be produced using three different processes. Each process has a unique cost associated with it. The CEO wants to know if the manufacturing processes are related to the overall cost of bike frame production. The following contingency table gives the number of bike frames produced with each process and cost level. At a significance level of .05, perform the chi-square test of independence to determine if production process is related to production cost.

5.99 CRITICAL VALUE
12.56 CHI SQUARE VALUE

### 5. Question : In the past, of all the students enrolled in "Basic Business Statistics" 10% earned A's, 20% earned B's, 30% earned C's, 20% earned D's and the remaining 20% either failed or withdrew from the course. Dr Johnson is a new professor teaching "Basic Business Statistics" for the first time this semester. At the conclusion of the semester, in Dr. Johnson's class of 60 students, there were 10 A's, 20 B's, 20 C's, 5 D's and 5 W's or F's. Assume that Dr. Johnson's class constitutes a random sample. Dr Johnson wants to know if there is sufficient evidence to conclude that the grade distribution of his class is different than the historical grade distribution. Use a = .05, and determine if the grade distribution for Dr. Johnson's class is different than the historical grade distribution.

Reject the null hypothesis at the 5% level of significance because 16.4 > 9.48 Therefore there is a difference between the historical grade distribution and Dr. Johnson's

True

False

### In general, the degrees of freedom in a contingency table are equal to:

(rows -1)(columns-1)

True

False

18, 21, 15

21, 16.53, 23

X 17.53, 16, 21

73%

Z, increases

Wider than

### When the population is normally distributed, population standard deviation s is unknown, and the sample size is n = 15; the confidence interval for the population mean µ is based on:

The t distribution

2.865 to 3.136

4

15.56

17.16

### You have diligently collected your surveys and crunched all of the numbers for your primary research on your IRP. One of the questions you asked was as folows: The Orrville Public Library would see an increase in number of customers if they extended their evening hours to stay open until 11:00 pm on weekend nights. You had 57 surveys collected from library adminstrators and staff, with 39 Agree and 10 disagree. Based on the calculated Chi-square value from above, what is the critical value you will compare that to and is this data now proven to be significant?

The critical value is 3.84, an yes it is significant

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