D-DS-FN-23 Dell Data Science Foundations 2023 Online Dumps

1. In a decision tree, what is an example of a pure node?

2. When would you prefer a Naive Bayes model to a logistic regression model for classification?

3. What is an appropriate assignment for a data scientist?

4. What is the output format from the Map function of MapReduce?

5. What does the R code z <- f[1:10, ] do?

6. What is a core deliverable at the end of the analytic project?

7. Consider the following SQL statement:

SELECT employee_id, year, salary, avg(salary)

OVER

(PARTITION BY employee_id ORDER BY year ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) as result_1

FROM employee

ORDER BY employee_id, year

For each employee_id, what is returned as result_1?

8. What is the mandatory Clause that must be included when using Window functions?

9. In a fitted ARIMA(1,2,3) model, how many differences are applied?

10. If R factors are categorical variables, which data classification level are they most closely related?

11. Consider this SQL statement:

SELECT product, prod_cost, avg(prod_cost) OVER (PARTITION BY product)

FROM product_detail

The OVER clause makes this what type of function?

12. In a Student's t-test, what is the meaning of the p-value?

13. Consider these itemsets:

(hat, scarf, coat)

(hat, scarf, coat, gloves)

(hat, scarf, gloves)

(hat, gloves)

(scarf, coat, gloves)

What is the confidence of the rule (gloves -> hat)?

14. During the data preparation phase, you notice a high correlation between average spend on video games, age of players, and number of science fiction shows watched.

Which technique could you use to address the three correlated variables?

15. You are attempting to find the Euclidean distance between two centroids:

Centroid A's coordinates: (X = 2, Y = 4)

Centroid B's coordinates (X = 8, Y = 10)

Which formula finds the correct Euclidean distance?

16. In linear regression modeling, which action can be taken to improve the linearity of the relationship between the dependent and independent variables?

17. Which chart type is intended to display correlations between sets of numeric data?

18. What does the Receiver Operating Characteristic (ROC) curve show?

19. A fair six-sided die is rolled. Let A denote the event that an odd number is rolled. Let C denote the event that a 1, 2, or 3 is rolled.

What is the value of the conditional probability, P(C|A)?

20. Which word or phrase completes the statement? Business Intelligence is to ad-hoc reporting and dashboards as Data Science is to __________.

21. Which method is used to solve for coefficients b0, b1, .., bn in your linear regression model: Y = b0 + b1x1+b2x2+….+bnxn

22. What is one modeling or descriptive statistical function in MADlib that is typically not provided in a standard relational database?

23. Refer to the exhibit.





You are using K-means clustering to classify customer behavior for a large retailer. You need to determine the optimum number of customer groups. You plot the within-sum-of- squares (wss) data as shown in the exhibit.

How many customer groups should you specify?

24. Which activity is performed in the Operationalize phase of the Data Analytics Lifecycle?

25. Which word or phrase completes the statement; “A theater actor is to ‘artistic and expressive’ as a data scientist is to.”?

26. When is the GROUP BY ROLLUP clause used in an OLAP query?

27. You have run the association rules algorithm on your data set, and the two rules {banana, apple} => {grape} and {apple, orange}=> {grape} have been found to be relevant.

What else must be true?

28. Which type of numeric value does a logistic regression model estimate?

29. You are having a discussion with a business colleague. The colleague mentions that they want to perform K-means clustering on text file data stored in HDFS.

Which tool should be recommended?

30. In which phase of the data analytics lifecycle do Data Scientists spend the most time in a project?

31. Your colleague, who is new to Hadoop, approaches you with a question. They want to know how best to access their data. This colleague has a strong background in data flow languages and programming.

Which query interface would you recommend?

32. What is a consideration when building decision trees?

33. You need to run a hypothesis test across three normally distributed populations.

Which technique should you use?

34. The Marketing department of your company wishes to track opinion on a new product that was recently introduced. Marketing would like to know how many positive and negative reviews are appearing over a given period and potentially retrieve each review for more in- depth insight.

They have identified several popular product review blogs that historically have published thousands of user reviews of your company’s products. You have been asked to provide the desired analysis.

You examine the RSS feeds for each blog and determine which fields are relevant. You then craft a regular expression to match your new product’s name and extract the relevant text from each matching review.

What is the next step you should take?

35. Which process in text analysis can be used to reduce dimensionality?

36. Which analytical method is considered unsupervised?

37. Refer to the exhibit.





Which type of data issue would you suspect based on the exhibit?

38. You have created a Logistic Regression model to predict customer churn for your company. The company’s Marketing department wants to use your model to identify at-risk customers and offer incentives to keep them from leaving.





Using two different thresholds for the model provides the two confusion matrices shown in the graphic. Marketing understands the relative costs of missing at-risk customers versus offering incentives to customers who are not at risk. Therefore, you need their advice on how to set the appropriate threshold on the churn model.

You are meeting with the Marketing team. In the meeting, you plan to state: “Raising the threshold from 0.5 to 0.75 reduces the number of unnecessary incentives that can be offered, at the cost of missing more of the customers who churned.”

What is the most appropriate visual to reinforce this statement?

A)





B)





C)





D)

39. Your customer provided you with 2, 000 unlabeled records and asked you to separate them into three groups.

What is the correct analytical method to use?

40. How is dimensionality defined in a "bag of words" document representation?

41. You received 100,000 home loan records and want to quickly determine if there is any correlation between mortgage age and mortgage amount before conducting advanced analysis.

Which tool should be used for the preliminary analysis?

42. What is the output of the K-means clustering algorithm?

43. You are provided with the following list.

Which window function is missing?

cume_dist()

dense_rank()

rank()

percent_rank()

first_value()

last_value()

lag()

lead()

ntile()

44. In text analysis, what makes the corpus representation dynamic?

45. How are window functions different from regular aggregate functions?

46. You have created a Linear Regression model to predict total sales based on variables M, N, P and Q as shown in the graphic. You originally expected all variables to have positive coefficients.





Which action would you take?

47. You have been assigned to do a study of the daily revenue effect of a pricing model of online transactions. All the data currently available to you has been loaded into your analytics database; revenue data, pricing data, and online transaction data.

You find that all the data comes in different levels of granularity. The transaction data has timestamps (day, hour, minutes, seconds), pricing is stored at the daily level, and revenue data is only reported monthly.

What is your next step?

48. Which key role for a successful analytic project can provide business domain expertise with a deep understanding of the data and key performance indicators?

49. A Data Scientist is assigned to build a model from a reporting data warehouse. The warehouse contains data collected from many sources and transformed through a complex, multi-stage ETL process.

What is a concern the data scientist should have about the data?

50. You have just completed the Discovery phase of a project and finished interviewing the main stakeholders. You have identified the necessary data feeds and are now beginning to set up the analytic sandbox.

What is the next step?

51. In which lifecycle stage are appropriate analytical techniques determined?

52. What is holdout data?

53. In a t-test with unknown variance, what values are used to calculate the t-statistic?

54. Which participant in a data analytics project is typically responsible for assessing the validity of the model?

55. In a user-defined aggregate function, what is SFUNC?

56. What is required in a presentation for project sponsors?

57. Consider the following itemsets:

(hat, scarf, coat)

(hat, scarf, coat, gloves)

(hat, scarf, gloves)

(hat, gloves)

(scarf, coat, gloves)

If the minimum support is 50%, what represents the complete list of frequent 2-itemsets?

58. Which activity is performed in the Operationalize phase of the data analytics lifecycle?

59. Which ROC curve represents a perfect model fit?

A)





B)





C)





D)

60. Which Hadoop service is responsible for requesting resources for, and monitoring the completion of, MapReduce processes?

61. To ensure a successful analytic project, which key role can consult and advise the project team on the value of end results and how these will be used on a daily basis?

62. Which word or phrase completes the statement? Emphasis color is to standard color as _______.

63. A data scientist is preparing a presentation for a meeting with the project’s business sponsors. The distribution of per-sale revenue is an important finding from the analysis. The graphics illustrate four ways to plot the per-sale revenue distribution..”





Which graphic is most appropriate for the sponsor presentation?

64. You have been assigned to do a study of the daily revenue effect of a pricing model of online transactions. You have tested all the theoretical models in the previous model planning stage, and all tests have yielded statistically insignificant results.

What is your next step?

65. A disk drive manufacturer has a defect rate of less than 1.0% with 98% confidence. A quality assurance team samples 1000 disk drives and finds 14 defective units.

Which action should the team recommend?

66. Data visualization is used in the final presentation of an analytics project.

For what else is this technique commonly used?

67. Refer to the exhibit.





What provides the decision tree for predicting whether or not someone is a good or bad credit risk.

What would be the assigned probability, p(good), of a single male with no known savings?

68. Which SQL OLAP extension provides all possible grouping combinations?

69. Assume you are performing an analysis to determine fraud detection on credit card usage. You will need to ensure higher-risk transactions. These may indicate that fraudulent credit card activity is retained in your data for analysis and not dropped as outliers during pre- processing.

What is the approach for loading data into the analytical sandbox for this analysis?

70. What type of data is represented in the exhibit?

71. When is a Wilcoxon Rank-Sum test used?

72. Refer to the Exhibit.





In the Exhibit. For effective visualization, what is the chart's primary flaw?

73. What requests resources from YARN during a MapReduce job?

74. Since R factors are categorical variables, they are most closely related to which data classification level?

75. What is a distinct property of Logistic Regression compared with Linear Regression?

76. You are building a logistic regression model to predict whether a tax filer will be audited within the next two years. Your training set population is 1000 filers. The audit rate in your training data is 4.2%.

What is the sum of the probabilities that the model assigns to all the filers in your training set that have been audited?

77. Consider the example of an analysis for fraud detection on credit card usage. You will need to ensure higher-risk transactions that may indicate fraudulent credit card activity are retained in your data for analysis, and not dropped as outliers during pre-processing.

What will be your approach for loading data into the analytical sandbox for this analysis?

78. What is an appropriate data visualization to use in a presentation for an analyst audience?

79. How is HDFS defined?

80. Which word or phrase completes the statement? Structured data is to OLAP data as quasi- structured data is to

81. You have been assigned to run a logistic regression model for each of 100 countries, and all the data is currently stored in a PostgreSQL database.

Which tool/library would you use to produce these models with the least effort?

82. A data scientist plans to classify the sentiment polarity of 10, 000 product reviews collected from the Internet.

What is the most appropriate model to use? Suppose labeled training data is available.

83. What does R code nv <- v[v < 1000] do?

84. You have run a Linear Regression model on the data shown in the graphic.





Which value is a reasonable guess for R-squared?

85. You have created a scatterplot of two continuous variables for 2000 records. You want to add a line to the scatterplot to check linearity of the data.

Which function would best address this need?

86. Why do the Naïve Bayesian classifier implementations use the log of probability value rather than the pure probability value?

87. Consider the following SQL query:

SELECT product_id FROM supplier_A

UNION

SELECT product_id FROM supplier_B;

What is the expected result?

88. In data visualization, which type of chart is recommended to represent frequency data?

89. Which word or phrase completes the statement; “Excessive emphasis color is to Bar chart as __________________.”?

90. You submit a MapReduce job to a Hadoop cluster. Although the job was successfully submitted, you notice that it is not completing.

What should be done?

91. Trend, seasonal, and cyclical are components of a time series.

What is another component?

92. Variable D is not significantly impacting the dependent variable.

After seeing your findings, the majority of your team agreed that variable B should be positively impacting the dependent variable.

What is a possible reason the coefficient for variable B was negative and not positive?

93. Refer to the exhibit.





You have run a linear regression model against your data, and have plotted true outcome versus predicted outcome. The R-squared of your model is 0.75.

What is your assessment of the model?