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Biostatistics > Experimental Designs > Flashcards

Experimental Designs Flashcards

1
Q

determines the way sample is selected

A

experimental design/sampling plan

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2
Q

in an ___ study, the experimenter observes the data that already exists

A

observational

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3
Q

plan for collecting data in an observational study

A

sampling pl

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4
Q

in a ____ experiment, the experimenter imposes one or more experimental conditions on the experimental units and records the response

A

designed experiment

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5
Q

is the object on which a measurement or measurements) is taken.

A

experimental unit

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6
Q

is an independent variable whose values are controlled and varied by the experimenter.

A

factor

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7
Q

is the intensity setting of a factor.

A

level

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8
Q

is a specific combination of factor levels.

A

treatment

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9
Q

is the variable being measured by the experimenter.

A

response

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10
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

what is the experimental unit

A

person

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11
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

what is the response

A

score on test

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12
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

what is the treatment

A

breakfast or no breakfast

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13
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

what is the factor

A

meal

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14
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

what is the levels

A

breakfast or no breakfast

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15
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

The experimenter in the previous example also records the person’s gender. Describe the factors, levels and treatments.

what is the factor #1

A

meal

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16
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

The experimenter in the previous example also records the person’s gender. Describe the factors, levels and treatments.

what is factor #2

A

gender

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17
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

The experimenter in the previous example also records the person’s gender. Describe the factors, levels and treatments.

what is levels of factor #1

A

breakfast or no breakfast

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18
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

The experimenter in the previous example also records the person’s gender. Describe the factors, levels and treatments.

what is levels of factor #2

A

male or female

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19
Q

A group of people is randomly divided into an experimental and a control group. The control group is given an aptitude test after having eaten a full breakfast. The experimental group is given the same test without having eaten any breakfast.

The experimenter in the previous example also records the person’s gender. Describe the factors, levels and treatments.

what are the treatments

A

male and breakfast
female and breakfast
male and no breakfast
female and no breakfast

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20
Q

in ANOVA, All measurements exhibit ____

A

variability

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21
Q

The total variation in the response measurements is broken into portions that can be attributed to various factors.

A

ANOVA

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22
Q

assumption of ANOVA

A

The observations within each population are normally distributed with a common variance σ^2

Assumptions regarding the sampling procedures are specified for each design
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23
Q

procedures are fairly robust when sample sizes are equal and when the data are fairly mound-shaped.

A

analysis of variance

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24
Q

three designs of experimental

A

completely randomized design

randomized block design

axb factorial experiment

25
Q

an extension of the two independent sample t-test.

A

completely randomized design

26
Q

an extension of the paired difference test.

A

randomized block design

26
Q

we study two experimental factors and their effect on the response.

A

axb factorial experiment

26
Q

A one-way classification in which one factor is set at k different levels

A

completely randomized design

26
Q

The k levels correspond to k different normal populations, which are the ___

A

treatments

27
Q

Is the attention span of children
affected by whether or not they had a good breakfast? Twelve children were randomly divided into three groups and assigned to a different meal plan. The response was attention span in minutes during the morning reading time.

What is the null and alternative hypothesis

A

Ho: There is no significant difference between the average attention span based on breakfast type

Ha: There is a significant difference between the attention span based on breakfast type

28
Q

why is it CRD

A

randomly assigned samples were placed into groups

29
Q

total sum of squares is divided into two parts

A

sum of squares for treatments
sum of squares for errors

30
Q

measures the variation among the k sample means.

A

sum of square for treatments

31
Q

measures the variation within the k samples.
in such a way that:

A

sum of squares for error

32
Q

F value is rejected when it is ___ than the f-critical value

A

greater

33
Q

Is the attention span of children
affected by whether or not they had a good breakfast? Twelve children were randomly divided into three groups and assigned to a different meal plan. The response was attention span in minutes during the morning reading time.

F value is 5.00
F crit = 4.26

what is the decision

A

reject Ho

34
Q

identify which of the three averages is the source of difference

A

Post-Hoc test

35
Q

Designed to test all pairs of population means simultaneously, with an overall error rate of a.

A

Tukey’s Method for Paired Comparisons

36
Q

Tukey’s Post Hoc test Assume that the sample sizes are ___and calculate a “ruler” that measures the distance required between any pair of means to declare a significant difference.

A

equal

37
Q

Is the attention span of children
affected by whether or not they had a good breakfast? Twelve children were randomly divided into three groups and assigned to a different meal plan. The response was attention span in minutes during the morning reading time.

Tukey

Full Light = 0.693
Full No = 0.120
Light No = 0.033

interpret

A

Light breakfast has the significant difference between No breakfast

38
Q

A direct extension of the paired difference or matched pairs design.

A

randomized block design

39
Q

A two-way classification in which k treatment means are compared

A

randomized block design

40
Q

The design uses blocks of k experimental units that are relatively similar or homogeneous, with one unit within each block randomly assigned to each treatment.

A

randomized block design

41
Q

total number of observations in RBD

A

n = bk

42
Q

two factors in rbd

A

treatments
blocks

43
Q

if 3 treatments, and 3 locations are there (block) what is the total number of observations

A

9

44
Q

we want to investigate the effect of 3 methods of soil preparation on the growth of seedlings. Each method is applied to seedlings growing at each of 4 locations and the average first year growth is located

what is the Ho and Ha

A

H0: No difference in average growth among soil preparation methods.
H1: There is a difference in average growth among soil preparation methods.

45
Q

we want to investigate the effect of 3 methods of soil preparation on the growth of seedlings. Each method is applied to seedlings growing at each of 4 locations and the average first year growth is located

what is the treatment and block

A

soil prep - treatment
location - block

46
Q

ANOVA for RBD is divided into three

A

sum of squares for treatments
sum of squares for blocks
sum of squares for error

47
Q

A randomized block design should not be used when treatments and blocks ___ correspond to experimental factors of interest to the researcher

A

both

48
Q

Remember that blocking may not always be ___.

A

beneficial

49
Q

Remember that you cannot construct ___intervals for individual treatment means unless it is reasonable to assume that the b blocks have been randomly selected from a population of blocks.

A

confidence

50
Q

A two-way classification in which involves two factors, both of which are of interest to the experimenter.

A

axb factorial experiment

51
Q

The replications allow the experimenter to investigate the interaction between factors A and B

A

a x b factorial experiment

52
Q

Interaction describes the effect of one factor on the behavior of the other. If there is no interaction, the two factors behave ___.

A

independently

53
Q

A drug manufacturer has two
supervisors who work at each of three different shift times. Do outputs of the supervisors behave differently, depending on the particular shift they are working?

what is Ho and Ha

A

H0: There is no significant interaction between the supervisor and the shift
H1: There is no significant interaction between the supervisor and the shift

54
Q

analysis of variance SS for axb is divided into four

A

sum of squares for factor a
sum of squares for factor b
sum of squares for interaction
sum of squares for error

55
Q

Once Ho is rejected in interaction, is there a need to look at p values of factor a and b?

A

no

Biostatistics (10 decks)

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