Strategy & Math Flashcards

Question

Scalar or Vector? velocity

Answer 1

1. Can I **visualize** it? 2. Can I **draw** a picture/graph/diagram of it? 3. Can i explain it to someone in **layman's** terms? 4. Can i think of and describe real-life **examples**?

Answer 2

**A****_tri****=1/2 bh**

Answer 3

**V_sphere=4/3 πr³**

Answer 4

SSISDDODIOSD

Answer 5

deltaf/fs=v/c

Answer 6

Qualifiers (Write these down!) "StrengthensNot ExceptWeakensLeast"

Answer 7

sin0T=Frsin0

Answer 8

Create compound fraction: 5x2=10, left w/ 3/5 13/5 becomes 2x (3/5)

Answer 9

"High/Low" methodChange denominator to 1 digit higher or 1 digit lowerex:3/7 changed to 3/6 and 3/8. Must be a little less than .5

Answer 10

You add them together

Answer 11

You subtract them

Answer 12

**=7.25** ## Footnote 4 x **7**=28 **¼** is left behind

Answer 13

* **√81**=9 * √**64**=8 ∴ the square root of 72 is somewhere **in between**, so about **8.5**

Answer 14

**SA****_sphere****= 4πr²**

Answer 15

sinθ=**O**pp/**H**yp cosθ=**A**dj/**H**yp tanθ=**O**pp/**A**dj "SOHCAHTOA"

Answer 16

* π radians=180° * 2π radians=360° There are approximately **6** radians in **ONE CIRCLE** * **∴,** if something is rotating at 12 rad/sec, it is making **2 revolutions/ sec**

Answer 17

* sin^-1 * ****_co_**secant** * cos^-1 * **secant** * tan^-1 * co**tangent**

Answer 18

tanθ=sinθ / cosθ

Answer 19

**X=½at²** ## Footnote 1. NON-linear 2. Linear 3. NON-linear

Answer 20

The log of an exponential function becomes linear, so exponential functions graphed on **semi**-log axes end up being **linear** * **...**AND a **linear** function would be **non**-linear If the exponential function is graphed on **log**-**log** axes, the function will be **non-linear** * The table below may be helpful* * The semilog graph described is for a **linear X-axis** and a **logarithmic Y-axis** (log-lin type not lin-log)

Answer 21

* A semi-log graph has a **logarithmic** scale on one axis, but a **linear** scale on the other axis

Answer 22

A log-log graph has a **logarithmic** scale on **BOTH** axes

Answer 23

**x∝t²** * If the distance traveled (x) increases by a factor of **three** (3), then time must increase by some factor that, when **squared**, will **also** equal a factor of three * This number is the **square root of three**, so time will increase by a factor of **1.7**—* * or be **1.7 TIMES larger** than it was originally*

Answer 24

a **Testable** hypothesis * basically, it can be used to verify a clear **YES** or **NO** answer

Answer 25

_**Experimental** or “Basic Science” Research_ * **Laboratory** research conducted in a **highly controlled environment;** * **NOT** on human subjects! * This type of research allows investigators to have the strictest level of **control** over all possible variables and conditions * Experimental research is therefore thought to be the most **reliable** way to indicate **CAUSATION**

Answer 26

**_Human Subjects Research_** ***2 Types: Experimental & Observational*** * Research conducted **outside** the laboratory, often on **human** subjects * _Drug trials_ are a common and familiar example * Has less control over conditions than in "**Basic Science"** research* * making conclusions **less** definitive* * For example, a study drug may **fail** to show decreased blood pressure in some subjects * However, it is **later** discovered that all participants did **not** follow the strict low-sodium diet required by the study guidelines * This was thought to influence blood pressure measurements in those patients

Answer 27

* Research involves a specific **intervention** controlled by the **investigator** * Subjects are separated into **control** and **treatment** groups. * e.g., To test the efficacy of a new drug, patients with allergies are separated into groups randomly and given either the **drug** (treatment) or **placebo** (control)

Answer 28

* Investigator observes data **WITHOUT:** * ****Direct control over the variables, **OR** * Implementation of interventions _Example_: An investigator reviews case studies from COPD [chronic obstructive pulmonary disease] patients and examines demographic information and lifestyle choices in an attempt to identify risk factors associated with COPD)

Answer 29

***DO GOOD.*** ## Footnote * Doctors and researchers have an obligation to promote the welfare of patients or study participants * Patient welfare should always be a primary consideration in study design and execution _ENDING A STUDY BECAUSE OF **POSITIVE** ("GOOD") RESULTS_: * One classical application of beneficence in human subjects research is the obligation to END an experimental study when it is clear a drug or intervention results in obvious benefit * This may sound **counterintuitive**, but remember that each study **must** have control groups * If a drug is found to save the lives of dying cancer patients..... * it is **NOT** ethical to continue the study long-term and thereby save the lives of those in the treatment groups * *...while those in the control groups are **withheld** from taking a drug researchers _know_ could help them*

Answer 30

**DO NO HARM** ## Footnote * This is the physician’s oath, but applies equally to **researchers** * Doctors and researchers have an obligation to not harm their patients or study participants _ENDING A STUDY BECAUSE OF **NEGATIVE** ("BAD") RESULTS:_ * Researchers are similarly obligated to end a research study *as soon as* it is verified that a treatment **harms** the subjects * Most early research that is criticized today is drawn into question because it violated this principle * The famous psychology study involving “Little Albert,” for example, while revealing evidence about conditioning, is now thought to have had an **unethical** impact on the young child involved :( * Albert was conditioned to have severe generalized phobias of animals and the study involved obvious emotional trauma to Albert.

Answer 31

**_Patient autonomy and informed consent_** * Physicians and researchers have an obligation to: * **Inform** patients or study participants, and * Allow them to **make decisions** about their own health and treatment At times, *some* deception (e.g., placebo) is **necessary** to effect research * However, this should be the **minimal** amount possible, the truth should be revealed as **soon** as possible, and deception in general should be approved by an Internal Review Board (IRB)

Answer 32

Equal **treatment** of all people * Equal allocation of **resources**, to the extent possible * ..without bias, prejudice or discrimination.

Answer 33

**_Cohort Study_** * is a **longitudinal** study observing characteristics (usually risk factors) of members of a cohort across time Cohort studies usually employ **correlations** to demonstrate a **relationship** _EXAMPLES:_ * Smokers (Cohort A) were three times **more** likely to develop lung cancer before the age of 50 than non-smokers (Cohort B) * A statistically significant correlation (r = 0.84, p \< 0.01) exists between socioeconomic status and frequency of pre-term births Notice that this is **NOT** the manipulation of an independent variable, **THEN** observing outcomes * Scientists are simply observing data about people or populations **as it exists** and **looking for relationships**

Answer 34

**_Cross-Sectional study_** * is the analysis of data collected from a population or sample **AT ONE SPECIFIC TIME** * ...compared to ***across a time period*** for cohort studies _EXAMPLES:_ * A survey of the U.S. population to determine the current prevalence of a disease * A study examines blood pressure among those with incomes above $100K/year and those below $100K.

Answer 35

**_Case-Control Study_** *By design, a Case-Control Study is always **RETROSPECTIVE*** * Is an observational study of individuals in the population **WITH** a condition present * ...and comparison of that group to a control group of persons **WITHOUT** the disease **IN THAT SAME POPULATION** (i.e., "reference group") *Most famous Case-Control Study is the one is the study that linked **lung cancer** to **smoking*** _EXAMPLE_: * There is a suspicion that zinc oxide (the white non-absorbent sunscreen traditionally worn by lifeguards) is **more** **effective** at preventing sunburns that lead to skin cancer than absorbent **sunscreen lotions** * A case-control study was conducted to investigate if exposure to zinc oxide is a more effective skin cancer prevention measure * The study involved comparing a group of former lifeguards that **HAD** developed cancer on their cheeks and noses (cases) to a group of lifeguards (same population) **WITHOUT** this type of cancer (controls) * ...and assess their prior exposure to: * zinc oxide **OR** * absorbent sunscreen lotions * This study would be **retrospective** in that the former lifeguards would be **asked to recall** ("Recall Bias") _which type_ of sunscreen they used on their face and approximately _how often_

Answer 36

*Useful for RARE outcomes*

Answer 37

**_INDEPENDENT VARIABLE_** * The variable that gets: * **MANIPULATED** (or rather...) changed **_BY THE INVESTIGATOR!!_** * Also called the “**predictor** variable.” It can be thought of as the “**CAUSE**” * Always goes on the **X**-axis **_DEPENDENT VARIABLE_** * The variable ***MEASURED*** * ....as a *response to changes* in the **IN**dependent variable * Also called the “**outcome variable**” It can be thought of as the “**EFFECT**” * You can't "Add" a ***De**pendent* Variable * i.e., you can "add" an outcome...you can only "add" something that **will** **change** the outcome * Always goes on the **Y**-axis

Answer 38

1. Independent: Time Spent studying * Dependent: Test score 2. Independent: Octane rating of gas * Dependent: Gas mileage 3. Independent: Dosage of medication * Dependent: Survival Rate 4. Independent: Exposure to violent VG's * Dependent: Lvl of aggression

Answer 39

**_Control Group_** A group or trial in which ***ALL*** conditions and environmental factors are ***IDENTICAL*** to the treatment group-- ***EXCEPT*** for the treatment itself!!

Answer 40

**_POSITIVE control_** * Is a group given a treatment with a **KNOWN** **OUTCOME** PURPOSE: * The positive control can be **compared** to the **unknown** outcome of whatever treatment is being studied _EXAMPLE_: * If your experiment results in the ability of bacteria to grow on a petri plate containing antibiotic, your **positive** control will be bacteria that are **known** to carry the appropriate drug resistance marker Even if **none** of your experimental bacteria grow, as long as there is growth of the positive control * ....you know that growth was at least **POSSIBLE**

Answer 41

**_NEGATIVE control_** * is a group that does **NOT** receive any condition or treatment * ...and for which **NO** outcome is expected PURPOSE: * To help expose **CONFOUNDING** variables _EXAMPLE_: * *An experiment results in the ability of bacteria to grow on a petri plate containing antibiotic* **NEGATIVE** Control: * Bacteria which do **NOT** carry a drug resistance marker should **NOT** be able to grow on a petri plate containing antibiotic ∴ if growth **IS** observed, it is a red flag that **something is WRONG** with the experiment! * *"What could be one reason for growth?"* * *aka what could be a confounding variable here?*

Answer 42

**_Selection Bias_** The method used to *_select_* participants is **NOT** **_TRULY_** **RANDOM** * ∴ * the results are **not** representative of the **whole** population * There are "**systematic** **BASELINE differences"** among participants ....because **true** randomization was **not** achieved

Answer 43

**_SPECIFIC REAL AREA BIAS:_** * is bias introduced by conducting the study **in a specific area** that does **NOT** include a representative sampling *of the population being studied* _For example:_ * A study of U.S. eating habits (population= U.S. citizens) conducted **at the gym** leaves out all those who do **not** attend the gym—particularly bad because: * being a member of a gym is likely to **confound** with eating habits *Having a **specific** **location** for a study does **NOT** **always** mean "specific real area bias" will exist!* _For example:_ * a study investigating the drug-using habits of Maricopa County High School students (population=HS students) would **not** be biased if conducted **only** at the high school * because the **sample** would be **representative** of the population

Answer 44

**_Self-Selection bias_** * is bias introduced when participants in the study have the ability to: * **choose** to **participate** or **not to participate**, OR , * to **determine** their **level of involvement** ***Surveys** show significant self-selection bias* _For example:_ * Feedback boxes at fast-food establishments are **far** from representative of customer opinions * Generally because those with **negative** opinions have been shown to be far **more** **likely** to fill out such surveys * (as opposed to those with positive experiences)

Answer 45

**_Pre-Screening or Advertising Bias:_** * Occurs when the **screening** or **advertising** _***PROCESS*** ***ITSELF***_ results in * *...an **un**representative sample* _For example:_ * Advertisements asking for volunteers FOR THE **SAME** STUDY that are worded: * “Volunteers needed for an **obesity** study” OR * “Volunteers needed for a **weightloss** study” ...*will likely elicit **different volunteers*** (Obesity=BAD! Weightloss=GOOD!)

Answer 46

**_Exclusion Bias_** * Refers to the exclusion of an **entire** **group** from the population _Example:_ * A study about **childhood education** that does *not survey* any **homeschooled** children

Answer 47

**_Healthy User Bias_** * When the persons included in the study are likely to be **healthier** * ....than the ***general*** population _Example:_ * Studying cardiac **atherosclerosis** among participants in a **triathalon**

Answer 48

**_Berkson’s Fallacy_** * Is the selection of participants from **hospitals**-- * ****where the participants are likely to be **LESS** **healthy** than the general population Is the **OPPOSITE EFFECT** of the Healthy-User Bias

Answer 49

**_OVERmatching_** Matching on variables **other** than those that are risk factors for the disease under study * Is a **negative** outcome resulting from what is normally a **good** practice: * matching for **potentially confounding variables*** * i.e., age-matched _EXAMPLE_: * If you use **neighborhood controls** in a study on **NUTRITION** and **TUBERCULOSIS**... * You are inadvertedly matching for **SES** (and thus, **nutrition**)*

Answer 50

**_OBSERVER BIAS:_** Observers (or researchers) **KNOW THE GOALS** of the study or the hypotheses * *...and allow **this** knowledge to **INFLUENCE** their observations during the study* _Foot Study Example_: * We **want** statistically significant data, so we "observe" things in a way that will help us **get** statistically significant data

Answer 51

**_Demand Characteristics_** * **PARTICIPANTS** form an **interpretation** of the experiment's **purpose** * ...and unconsciously **change** their behavior* * to **FIT** that interpretation* _Example_: * During doming trials, we remark how subject's numbers were the "highest we've seen" * This makes them think we **WANT** to see higher numbers * They then strive to get the **highest numbers possible** *(In reality, we want NATURAL doming strengths)*

Answer 52

**_Information Bias_** **=Wrong** or **inexact** recording of variables or data * With **CONTINUOUS** Variables (such as *blood pressure*): * this is referred to as _"**Measurement Error"**_ * With **CATEGORICAL** Variables (such as *tumor stage*): * this is known as **_"Misclassification"_** ****_Example_: * Continuous (measurements) * recording them wrong * Categorical (shoe size on form) * you put down the wrong shoe size for them

Answer 53

**_Confounding Variables_** (a.k.a. confounding factor, confounder) * An extraneous variable that **INFLUENCES** the variables being studied * *....but is **NOT** part of the **_expected_** correlation or causal pathway being investigated* _EXAMPLE_: * Suppose the relationship between A and B is being investigated * A is hypothesized to **increase** B * Experimental results **support** this hypothesis * It is **later** discovered that a **third** variable (i.e., **extraneous** variable) influences both A **and** B, * Decreasing A, and * Increasing B * In fact, it was C that **created** the observed result in B that was **originally** attributed to A ***Variable C is a confounding variable*** **_Placebo Effect:_** * One **example** of a confounding variable * The placebo effect occurs when participants given a placebo (i.e., sham treatment) during a study experience REAL or PERCEIVED health benefits-- * due to their belief that they ARE being treated

Answer 54

**_Detection Bias_** * Systematic **differences** **between** **groups...** * ...caused by _inconsistency_ in* * the **method of detection** or **diagnosis*** _EXAMPLE:_ * A study reports that inner city children suffer from ADHD at **twice** the rate of suburban children It is **later** discovered that systematic differences existed between: * **diagnostic tools,** and * **training available** * ...at **inner city** hospitals included in the study * ...vs. **suburban** hospitals included in the study * Basically, they're detecting ADHD rates *inconsistently,* because suburban hospitals are able to more accurately diagnose those who **REALLY** have ADHD * Inner city hospitals are quicker to just "slap a label" on 'em

Answer 55

**_Performance Bias_** * Systematic differences between groups... * in terms of the* ***_ACTUAL_ CARE OR TREATMENT PROVIDED*** _EXAMPLE_: * A physician *unconsciously* pays **closer** attention to and conducts **more** followup with patients the doctor **knows** to be enrolled in a heart study This results in differences in care for those individuals **not** accounted for in the study

Answer 56

**_Experimenter Bias_** (a.k.a., **Researcher** Bias) * ERRORS introduced into a study ***due to the expectations of the _investigator_*** * _2 Types:_ 1. **Confirmation** Bias 2. **Reporting** Bias Experimenter Bias also can include unconscious **communication of expected results** to the participants * ...thereby influencing their **behavior**

Answer 57

**_Confirmation Bias:_** * The tendency to **favor** information that **confirms** one’s hypothesis or preconceived notions * and to **dismiss** information that **discredits** them (This sort of thing also happens *psychologically)*

Answer 58

**_Reporting Bias:_** * Systematic differences resulting from **some** findings being reported and **other** findings **NOT** being reported * Investigators may withhold or ignore data that **does not** support their hypothesis (if conscious and intentional this would be a clear violation of ethics) Statistically-significant results are usually **_far more likely to be reported_** than are statistically **in**significant results ...although **BOTH** are important to an ***unbiased*** determination

Answer 59

**Accuracy** * is a measure of the degree to which a value represents the **true** or **correct** value **Precision** * is a measure of the degree to which repeatedly measured values show the **same** or **reproducible** values * The **greater** the range or **scatter** of measurements, the **less** precision

Answer 60

**_RELIABILITY_** * Results are **consistent** and **repeatable** **_VALIDITY_** * The test or experiment measures what it **purports** to measure * ...and uses methods that **meet scientific standards** ***Failure** **to adhere** to the **standards of the scientific method** or other accepted experimental **best** **practices** _results in **LOW** internal validity_*

Answer 61

_**"Test-Retest"** reliability_ * is a measure of the degree of consistency between **one** administration of a test and a **subsequent** administration **of** **that same test** (i.e. the “retest”) _**"Inter-Rater"** reliability_ * is a **measure of consistency** between multiple raters or evaluators that are assigning the **same** values or making the **same** observations *In both cases, a high value of reliability is around **1.0** and shows good **internal validity***

Answer 62

* If the volume goes down by 80%, it has lost **4/5** of its value— * which is the same as being multiplied by **1/5** * or going down by a factor of **5**

Answer 63

125% Same as multiplying it by 5/4

Answer 64

* Correlation coefficients relate to linear regression analysis * A large number of trials * involving **changes** in the **independent** variable * are graphed against the **dependent** variable *resulting in a **SCATTER PLOT*** * A “**Least Squares**” or “**Best Fit**” line is drawn * that **best** approximates the **trend** of the data points _*The correlation coefficient, r² is a measure of how tightly the **DATA** fit to **THIS** line!*_ The **CLOSER** the data are, as a whole, to the trend line: * the **HIGHER** the r² value

Answer 65

Correlation Coefficients vary from **0 to 1** * An r² value of **1.0** would be a **PERFECT** correlation! * The correlation coefficient is said to explain the amount of variance in **y** ACCOUNTED FOR by **x***

Answer 66

*Hill’s Criteria is a **SET OF GUIDELINES** used to evaluate whether or not a **CAUSAL RELATIONSHIP** exists* 1. **T**emporality 2. **C**onsistency 3. **D**ose-**R**eponse Relationship 4. **C**oherence 5. **P**lausibility 6. **T**estable by Experiment 7. **S**pecificity 8. **S**trength 9. **A**nalogy

Answer 67

_Temporality:_ *In time, the exposure or treatment* ***MUST PRECEDE THE OUTCOME*** * If A **causes** B, A **must** occur in time **prior** to B _This is often considered the **most important** Hill Criteria_ * If the outcome is found to occur **before** the exposure in even a few cases, the potential of causality is generally **REJECTED**

Answer 68

_Strength_ * The **MAGNITUDE** of the **CORRELATION** or association * *including statistical measures of **significance*** A **larger** correlation, **larger** r² value, or a **smaller p value** would all **support** causation

Answer 69

**_Consistency:_** _The correlation or association:_ * continues across **MULTIPLE** trials, across time, or when the study is **REPLICATED** by others* * In other words, the relationship is **REPRODUCIBLE***

Answer 70

**_Specificity:_** *One of the **weakest** Hill Criteria* * High specificity means the potential cause results in only **ONE** specific effect * If present, it can provide **additional** support for causation-- * but the lack of specificity is common in **MANY** established cause-effect relationships

Answer 71

**_Plausibility:_** The association fits **LOGICALLY** within our current understanding of how a process works The association has a logical theoretical basis

Answer 72

**_Dose-Response Relationship:_** The observed **response** is **proportional to:** the **dosage** or **degree of the exposure** or **treatment** * This is considered **STRONG** evidence of causation* * ...but is **NOT** necessary*

Answer 73

**_Testable by Experiment:_** The **_ASSOCIATION_** can be: ***REPROD******UCED VIA EXPERIMENT***

Answer 74

**_Coherence_**: The **ASSOCIATION** is **COMPATIBLE** with: *existing or previously-established science*

Answer 75

**SIMILAR associations** are **shown** or **known** to exist that are: ***analogous to** the* *association being considered*

Answer 76

**_Internal Validity_** The extent to which you are able to say that: No **OTHER** variables (except the one **you're** studying) caused the result ...which is a function of the scientific **RIGOR** of the study

Answer 77

**_Necessary:_** A condition that **MUST** be satisfied in order for an event to occur **_Sufficient:_** A condition that, *_if satisfied_*, **GUARANTEES** that an event **WILL** occur!

Answer 78

*External Validity* = ***GENERALIZABILITY!*** ## Footnote =The degree to which the findings can be **extrapolated** to the **general** population *_This depends a lot on:_* *the **SUBJECTS** being tested-- are the representative of the **general** population?* Example: * Sarah is a psychologist who teaches and does research at an expensive, private college.She's interested in studying whether offering specific praise after a task will boost people's self-esteem. If her hypothesis is correct, then giving someone a specific compliment on a job well done after a task will make them feel better about themselves. And if she can show that specific praise post-task boosts self-esteem, then managers at companies everywhere will be able to boost their employees' self-esteem by offering them specific praise.* * But here's a **problem**: the volunteers that Sarah gets for her study are **all college students**, most of them are **white**, and most of them are from **privileged backgrounds*** ***Sarah worries that her results might not be applicable to people who are NOT in their late teens or early 20s, white, and rich***

Answer 79

_Information about:_ * The **study** itself * **Who** is in the... * Control groups * Treatment groups * other potentially **biasing** details _are concealed from:_ the person **DOING** the assessment

Answer 80

_Information about:_ * The **study** itself * **Who** is in the... * Control groups * Treatment groups * other potentially **biasing** details _are concealed from_ **BOTH:** 1. The **SUBJECT** 2. The person **DOING** the assessment (researcher) *

Answer 81

**_Type I Error:_** ***REJECTED H0** but **SHOULDN'T HAVE*** **CLAIMED** difference between groups ...when **NONE** existed **_Type II Error_*****SHOULD** **HAVE** rejected H0 but **DIDN'T*** Did **NOT** claim a difference between groups ...when one **DID** exist

Answer 82

**_The Null Hypothesis:_** H₀ is always the ***LACK OF*** A RELATIONSHIP OR GROUP DIFFERENCE _In testing for **GROUP** **DIFFERENCES:**_ * **H**₀= there are ***NO*** *statistically significant differences* between groups _When testing for **CORRELATION** or **CAUSATION**:_ **H₀**= there is ***NO* RELATIONSHIP**

Answer 83

_The Alternative Hypothesis:_ The ***PRESENCE*** OF A RELATIONSHIP OR GROUP DIFFERENCE _The **OPPOSITE** of the_ **H₀!** _In testing for **group** differences:_ * Alt. Hypothesis=there ***IS*** a difference between groups _When testing for **correlation** or **causation**:_ * Alt. Hypothesis= there ***IS*** a relationship.

Answer 84

**Sample =** * that portion of a population included in the data * [e.g., U.S. veterans called in the phone survey] _**SMALLER** than the **POPULATION**_ *which is **ALL** the members in the group/category being sampled* [e.g., **ALL** U.S. veterans]

Answer 85

* A statistic is a **measure** or **data point*** * (such as **mean**, **median**, etc.)* * that is calculated for the sample* [e.g., **average income** among U.S. veterans in a sample]

Answer 86

**_Parameter =_** *a measure (such as mean, median, etc.) that is calculated for the **ENTIRE** population,* ***NOT** merely the sample of the population* [e.g., average income among **ALL** U.S. veterans]

Answer 87

**MEAN**= * the **average** value **MEDIAN** = * the **middle** of the data **MODE**= * the **most frequently occurring** data point **RANGE**= * the **minimum** data point ⇒**maximum** data point

Answer 88

**STANDARD DEVIATION** **(SD)** = * how tightly **associated** the data are **TO THE _MEAN_** _A small SD indicates:_ a **narrow** set of data for which most values are close to the mean _A large SD indicates:_ a **greater spread**, or **wider** distribution, of the data around the mean

Answer 89

**_Normal Distribution=_** Hypothetical perfect ***BELL-SHAPED*** curve f_or which the following is true:_ * 1 SD = **68%** of the population * 2 SD = **95%** of the population * 3 SD = **99%** of the population

Answer 90

***_Assumption = Outcomes are:_*** 1. **INDEPENDENT** * *Do **NOT** influence one another* 2. **MUTUALLY EXCLUSIVE** * *They **CANNOT** occur together*

Answer 91

***_AND vs. OR_*** **AND =** * **MULTIPLY** *the probabilities of individual events to get the overall probability of* **BOTH** *events occurring* **OR =** * **ADD** *the probabilities of each individual event together to get the overall probability of* **EITHER** *event occurring*

Answer 92

***t-Test or z-Test ⇒p value*** The “test statistic” (either a **t-value** or a **z-value**) is calculated * This result is **COMPARED** to: * a **TABLE** of t-values or z-values ***_The table gives us:_*** *the **SIGNIFICANCE LEVEL, "**α," associated with that test statistic*

Answer 93

**z-test** * For a z-test, ***n\>30*** * *This will mean it has a **NORMAL (BELL-SHAPED) DISTRIBUTION*** * We'd use a t-test when our **sample size is** ***SMALL*** * This will mean our graph will **NOT** be normally distributed (only approximately)

Answer 94

Significance Level (α) * α = **0.05, 0.01, 0.001*** * **p \< 0.05** means we can be **95% confident** that the results are actual/**real** * ...**RATHER** than the result of random chance* * **p \< 0.01** means we can be **99% confident**, and so forth

Strategy & Math Flashcards

(174 cards)